Small theatrical rogue (5)
I believe the answer is:
scamp
'rogue' is the definition.
(I've seen this before)
'small theatrical' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'theatrical' becomes 'camp' (I've seen this before).
's'+'camp'='SCAMP'
(Other definitions for scamp that I've seen before include "pickle" , "Impish youngster" , "Mischief-maker" , "A young rascal misbehaving in camps" , "Rogue - perform inadequately" .)