Set up a portion of gin (4)
I believe the answer is:
trap
'gin' 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 trap that I've seen before include "Light horse-drawn carriage" , "mug" , "Bunker; carriage" , "that can let an actor down" , "Rock; carriage; gin" .)