Gangleader squeezed deficient composer for a drink (10)
I believe the answer is:
cappuccino
'for a drink' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for cappuccino that I've seen before include "Frothy coffee" , "Drink" , "Type of coffee" .)