Fellow of defiance (3)
I believe the answer is:
ian
'fellow' is the definition.
(common masculine name)
'of defiance' is the wordplay.
'of' says the answer is hidden in the clue.
'IAN' can be found hidden inside 'defiance'.
(Other definitions for ian that I've seen before include "- Fleming (James Bond)" , "Scotsman?" , "- McEwan, Eng. writer" , "- Botham, cricketer" , "The familiar Dr Paisley" .)