In the clutch means at perfect timing.

Comes from the clutch in a manual transmission where perfect timing can mean the difference between a launch and a stall)

When you see your friends being Clutch so you call out Clutch or Be Clutch.

When you are playing an online game , and you are the only one alive on your team.You have to "Clutch"the round by killing the opposing team single-handedly. So clutching is surviving in a one versus five or more players situation, killing them and winning the game . Clutching a situation in other words is getting control over a close situation.

When you are flashing a strap but don't pull the trigger or shot to kill.

Clutch; - Perfect, Exactly what is needed, (also used like "score" or "awesome", as an exclamation.)

Exactly what you need, exactly when you need it.

to perform under pressure