Small mostly submissive Barrie character (4)
I believe the answer is:
smee
'barrie character' is the definition.
(Mr Smee is a character in Peter Pan by JM Barrie)
'small mostly submissive' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'mostly' means to remove the last letter.
'submissive' becomes 'meek' (I've seen this before).
'meek' with its last letter taken away is 'mee'.
's'+'mee'='SMEE'
(Other definitions for smee that I've seen before include "Hook's bo'sun (Peter Pan)" , "Simpered oddly" , "Stage boatswain" , "Local duck" , "Captain Hook's mate" .)