Sell bike part mentioned (6)
I believe the answer is:
peddle
'sell' is the definition.
(I know that peddle is a more specific form of the action sell)
'bike part mentioned' is the wordplay.
'bike part' becomes 'pedal' ('pedal' is part of 'bike').
'mentioned' indicates a 'sounds like' (homophone) clue.
'pedal' is a homophone of 'PEDDLE'.
(Other definitions for peddle that I've seen before include "Travel around selling small items" , "Promote (an idea) widely or persistently" , "Deal illegally in (not a lever on a cycle!)" , "Sell goods illegally or promote ideas" , "traffic" .)