Brave worker is behind insolence (7)
I believe the answer is:
gallant
'brave' is the definition.
(similar in meaning)
'worker is behind insolence' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'is behind' is a charade indicator (letters next to each other).
'insolence' becomes 'gall' (synonyms).
'ant' put after 'gall' is 'GALLANT'.
(Other definitions for gallant that I've seen before include "markedly attentive to women" , "Valiant; courteous" , "Brave and honourable" , "lover" , "Flirt" .)