Plead to swap bicycle part (5)
I believe the answer is:
pedal
'bicycle part' is the definition.
(I know that bicycle has part or parts pedal)
'plead to swap' is the wordplay.
'to swap' indicates anagramming the letters (I've seen 'swaps' mean this).
'plead' with letters rearranged gives 'PEDAL'.
(Other definitions for pedal that I've seen before include "Foot-lever" , "Bicycle footrest" , "sustained note" , "Part of cycle" , "Plead for bicycle propeller" .)