Elbows locked and loaded.

Squeeze the bar as hard as you can. Lock your elbows at full extension. Rotate your elbows behind you, as if squeezing an orange in your arm pit.
Squeeze the bar
Grip the shit out of the bar, but leave your upper arms relaxed. Don’t try to row the bar when you’re deadlifting it. Always grip the bar harder than you need to.
Stronger By Science
Squeeze that bar like it owes you money. Never stop squeezing a bar with any lift - never ever stop squeezing as hard as you can!
Neversate
BURY YOUR HAND IN THE BAR
BURY YOUR HAND IN THE BAR
Lock your elbows
ARMS ARE MEAT HOOKS
ARMS ARE MEAT HOOKS
When I get my grip, the first thing I'm going to do is lock my arms as hard as I can. You want to think as if your elbow doesn't even bend. That elbow joint doesn't hinge at all. You just want to get these arms straight as possible. That's going to get... your lats locked in tighter. We'll get our grip, lock the arms hard, and then I'm going to rotate the elbows back... We'll just rotate our elbows towards your body. That'll get you even tighter again.
Animal
You need to imagine your arms as just hooks; you shouldn't have any bend in your elbows at the start of your pull. Lest you think this is just a minor distinction, simply "yanking" the bar with your arms is a fine way to wind up on the operating table with a torn biceps!
You can't effectively transfer force from your lower body and core to the bar if your elbows are flexed...this is a great way to rupture a biceps tendon and guarantee that you aren't pulling as heavy as you ought to be.
Rotate your elbows
ELBOWS BACK
ELBOWS BACK
When I now grab the bar, I want to pull myself into the floor and I'm thinking about screwing my lats. I'm going to screw the bar slightly and you're going to feel the change in position with your lats.
Omar Isuf
WRAP THE BAR AROUND YOU
WRAP THE BAR AROUND YOU
Kabuki Strength
Elbows will initiate a move in the shoulder as far as tightness goes...bringing them in close to the body and pointing them back a little bit further, that's one way of winding up the shoulder and getting more tightness. You're taking [your grip] and kind of screwing it in a little bit... so we go from a relaxed position to a loaded position as we get ready to pull.
Super Training
ROTATE ELBOWS
ROTATE ELBOWS
Super Training
SQUEEZE ORANGES
SQUEEZE ORANGES
whiteboard_daily
Use these two cues to further engage your lats: Protect your armpits. Squeeze an orange in your armpit.
[Imagine an orange in your armpit.] Squeeze the orange in the armpit. Make orange juice in the armpit... When people get set up, they're gonna squeeze the orange in the armpit so their lats are on, their upper back is nice and tight, and then they're going to come up and finish. But I don't want them to lose the shoulders on the way down, so they have to continue squeezing the orange on the way down so they keep a solid back position and keep that upright torso.
T-Nation
As she reaches down to grab the bar, if I was to come here and try and tickle her armpits, she's squeezing her tricep into her lat to block that... We're gonna squeeze the tricep into the lat and protect the armpit to create a rigid torso. Another way that you can think of this if you want to start from the top is to try and reach your arms down as long as you can. As I'm standing up right here and I push my arms down my side I'm not only elongated my arm, which is a great thing to do in the deadlift, I'm also engaging my lats very hard. I can reach down and maintain that same position.
Juggernaut
The next time you deadlift, think about someone tickling your armpits. Your goal is to try to stop them without using your hands.
Once my hips are in a good position, my next cue is thinking about locking in my lats... by trying to bend the bar across my shins like it is a horseshoe, but a lot of other people will get the idea of covering up their armpit with their shoulder or trying to make the triangle of your torso your arm and your thigh shrink. Some people talk about sticking their shoulder blades in their back pocket.
Neversate