Not the star part of Peter Rabbit (3)
I believe the answer is:
bit
'part of peter rabbit' is the definition.
'bit' can be an answer for 'part' (both mean a piece of something). I am unsure of the 'of peter rabbit' bit.
'not the star' is the wordplay.
I cannot really see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
The remaining letters 'bi' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bit that I've seen before include "The boring-piece of a drill" , "a curb?" , "Small piece - used teeth" , "Data measurement unit" , "Piece; horse's restraint" .)