Son leaves belt in corner (4)
I believe the answer is:
trap
'corner' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for trap that I've seen before include "Snaring device" , "Baited device" , "Light carriage - it's sometimes sprung!" , "Control ball" , "Deceive" .)