Sporty cyclist's end in ethical upset (8)
I believe the answer is:
Here is my best explanation:
'sporty' is the definition.
(I've seen this before)
'cyclist's end in ethical upset' is the wordplay.
'end' indicates one should take the final letters.
'in' indicates putting letters inside.
'upset' is an anagram indicator.
The final letter of 'cyclist' is 't'.
'ethical' anagrammed gives 'athleic'.
't' put within 'athleic' is 'ATHLETIC'.
(Other definitions for athletic that I've seen before include "Good at running and jumping", "With a strong and well proportioned body", "Given to partaking in sporting events", "Team", "Strong and active, good at sports", "Good at sports", "Lithe act (anag)", "Muscular", "Lithe cat (anag.)" and "Wigan, for example".)