Son leaving belt in corner (4)
I believe the answer is:
trap
'corner' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for trap that I've seen before include "that can let an actor down" , "Ambush" , "Rock; carriage; gin" , "Device to catch prey" , "that may be sprung?" .)