See you on cycles, a campus girl barely astride (2,6)
I believe the answer is:
au revoir
'see' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'you on cycles a campus girl barely astride' is the wordplay.
I cannot really see how this works, but
'you' could be 'u' (commonly used in online communication) and 'u' is found in the answer.
'on' could be 're' ('on' can be mean 'with reference to') and 're' is located in the answer.
'a' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for au revoir that I've seen before include "See you soon, 'bye for now - in France" , "Bye-bye! (Fr.)" , "'Goodbye to the French (2,6)'" , "cheers" , "So long, see you soon - in France" .)