Little boy is holding it (6)
I believe the answer is:
petite
'little' is the definition.
(similar in meaning)
'boy is holding it' is the wordplay.
'boy' becomes 'pete' ().
'is holding' means one lot of letters goes inside another.
'pete' placed around 'it' is 'PETITE'.
(Other definitions for petite that I've seen before include "Little French" , "Tie pet up, being small and dainty" , "Attractively small" , "Short" , "Small and attractive" .)