One part of Surbiton (3)
I believe the answer is:
bit
'one part' is the definition.
(both mean a piece of something)
'of surbiton' is the wordplay.
'of' indicates the answer is hidden within the clue.
'BIT' is hidden within 'surbiton'.
(Other definitions for bit that I've seen before include "Segment" , "Piece; horse's restraint" , "Cutting piece of a drill (3)" , "Snaffle - small piece" , "Binary digit; small piece" .)