Sideways look offered up, taking in bold defiant figure (5)
I believe the answer is:
rebel
'defiant figure' is the definition.
'sideways look offered up taking in bold' is the wordplay.
'sideways look' becomes 'leer' (to leer is to look at unpleasantly).
'offered up' is a reversal indicator.
'taking in' means one lot of letters goes inside another.
'bold' becomes 'b' (abbreviation).
'leer' backwards is 'reel'.
'reel' placed around 'b' is 'REBEL'.
(Other definitions for rebel that I've seen before include "Mutineer, one who defies authority" , "revolutionary" , "Anti-establishment figure" , "Revolt, mutiny" , "Bolshy" .)