Good and ready to complain (5)
I believe the answer is:
gripe
'complain' is the definition.
(griping is a kind of complaining)
'good and ready' is the wordplay.
'good' becomes 'g' (abbreviation).
'and' is a charade indicator (letters next to each other).
'ready' becomes 'ripe' ('ripe' can be similar in meaning to 'ready').
'g'+'ripe'='GRIPE'
'to' acts as a link.
(Other definitions for gripe that I've seen before include "Protest" , "Complain; stomach pain" , "Grumble informally" , "Keep on complaining" , "Grievance" .)