Agreed working to fix rug was a bugger! (9)
I believe the answer is:
earwigged
'was a bugger' is the definition.
(earwig can mean to secretly listen to or bug)
'agreed working to fix rug' is the wordplay.
'working' indicates anagramming the letters.
'to fix' means one lot of letters goes inside another (inserted letters are fixed in place).
'rug' becomes 'wig' ('rug' is an informal term for a wig).
'agreed' anagrammed gives 'earged'.
'earged' going around 'wig' is 'EARWIGGED'.
(Other definitions for earwigged that I've seen before include "Listened" , "Eavesdropped" , "Illicitly picked up" , "Overheard" .)