Such a victory as the road cleaner won over dirt? (8)
I believe the answer is:
sweeping
'the road cleaner won over dirt?' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I can't see?
'such a victory as' is the wordplay.
'such a victory' becomes 'sweep' (sweep is a kind of victory).
'as' becomes 'ing' (I can't explain this - if you can you should give a lot more credence to this answer).
'sweep'+'ing'='SWEEPING'
Can you help me to learn more?
(Other definitions for sweeping that I've seen before include "not very specific" , "clearing the floor?" , "Wide-ranging and comprehensive - also cleaning?" , "work for Mrs Mopp" , "Cleaning with a broom" .)