Don't persist when a chap is on short time (6)
I believe the answer is:
desist
'don't persist' is the definition.
I can't tell whether this defines the answer.
'a chap is on short time' is the wordplay.
'a chap' becomes 'des' ().
'on' is a charade indicator (letters next to each other).
'short time' becomes 't' (abbreviation for time).
'des'+'is'+'t'='DESIST'
'when' acts as a link.
Can you help me to learn more?
(Other definitions for desist that I've seen before include "Refrain (from doing something)" , "Cease (from doing something)" , "'Stop, give over (6)'" , "Leave off (doing a thing)" , "'Give over, refrain (6)'" .)