Fox sighted incredible British cyclist cycling (5-2)
I believe the answer is:
tally-ho
'british cyclist cycling' is the definition.
The definition suggests a singular noun which matches the answer.
'fox sighted incredible' is the wordplay.
I cannot quite understand how this works, but
'incredible' could be 'tall' (as in a tall tale) and 'tall' is located 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 tally-ho that I've seen before include "Fox-hunting cry" , "Huntsman's cry" , "Hunt cry" , ""I've seen the fox!"" , "Come on, hounds!" .)