So urge to resolve complaint (6)
I believe the answer is:
grouse
'complaint' is the definition.
(I've seen this before)
'so urge to resolve' is the wordplay.
'to resolve' indicates an anagram (I've seen 'resolved' mean this).
'so'+'urge'='sourge'
'sourge' is an anagram of 'GROUSE'.
(Other definitions for grouse that I've seen before include "Bellyache" , "Petty complaint" , "Bird - complaint" , "Game bird - beef" , "Complain pettily" .)