Contracted rubbish collector goes round travelling on two wheels (8)
I believe the answer is:
bicycles
'wheels' is the definition.
('bicycle' can be a synonym of 'wheel')
'contracted rubbish collector goes round travelling on two' is the wordplay.
I cannot really understand how this works, but
'round' could be 'cycle' (synonyms) and 'cycle' is found within the answer.
The remaining letters 'bis' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bicycles that I've seen before include "Two-wheeled vehicles" , "Wheeled vehicles" .)