Complain when a chap gets out for a duck (4)
I believe the answer is:
moan
'complain' is the definition.
(moan can mean to complain or whinge)
'a chap gets out for a duck' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is present in the answer.
'duck' could be 'o' (resembles zero - 'duck' in cricket) and 'o' is found in the answer.
A single letter 'm' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'when' is the link.
Can you help me to learn more?
(Other definitions for moan that I've seen before include "Express pain" , "Indicate pain" , "Complaint" , "Complain; rhymes with money lent" , "Beef" .)