Nice to see motorbike race in quarry (6)
I believe the answer is:
pretty
'nice' is the definition.
(I've seen this before)
'race in quarry' is the wordplay.
'race' becomes 'tt'.
'in' means one lot of letters goes inside another.
'quarry' becomes 'prey' (synonyms).
'tt' inserted within 'prey' is 'PRETTY'.
'to see motorbike' 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 pretty that I've seen before include "Attractive - quite" , "Pleasing on the eye" , "Facially attractive" , "Lovely" , "like a kettle of fish" .)