Pun about helper working as a volunteer? (6)
I believe the answer is:
unpaid
'working as a volunteer?' is the definition.
(volunteers are not paid)
'pun about helper' is the wordplay.
'about' indicates an anagram.
'helper' becomes 'aid' (something which helps).
'pun' anagrammed gives 'unp'.
'unp'+'aid'='UNPAID'
(Other definitions for unpaid that I've seen before include "Without wages" , "Outstanding, owing" , "Of bill, outstanding" , "Without reward" , "Overdue" .)