Sneer at a chap as you pinch his bike? (6)
I believe the answer is:
deride
'sneer at' is the definition.
'his bike?' is the wordplay.
'his' becomes 'de' (I am not sure about this - if you are sure you should believe this answer much more).
'bike?' becomes 'ride' (biking is a kind of riding).
'de'+'ride'='DERIDE'
'a chap as you pinch' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for deride that I've seen before include "Jeer, make little of" , "Ridicule, laugh at" , "Disparage" , "Ridicule, scoff at" , "Poke fun at" .)