to perform under pressure

Great, Essential, and Potent rolled into a single word. Clutch is also used to describe something that is done, not something that is.

n.
the crucial moment that comes between winning and losing

adj.
being able to perform under extreme pressure

coming through when you are needed most in high pressure situations

Exactly what you need, exactly when you need it.

The assembly that engages and disengages a transmission. Performing successfully while under pressure. A group of baby birds. A ladies handbag. A grasp or hold.

Originating in select areas of the University of Maryland, clutch is a noun used to describe a person who is, essentially, a bitch. A clutch is often the subject of jokes and is usually excluded from social events because of the bitch-assery that they tend to exhibit.