Wide hook used for carp (6)
I believe the answer is:
whinge
'carp' is the definition.
(both can mean to complain)
'wide hook' is the wordplay.
'wide' becomes 'w' (abbreviation e.g. in cricket).
'hook' becomes 'hinge' (hinge can mean a metal hook).
'w'+'hinge'='WHINGE'
'used for' acts as a link.
(Other definitions for whinge that I've seen before include "Complain peevishly" , "protest?" , "Complain fretfully" , "Complain annoyingly" , "Peevish complaint" .)