Very cool victory gained by effort (6)
I believe the answer is:
wintry
'very cool' is the definition.
'wintry' can be an answer for 'cool' (I've seen this before). I'm unsure of the 'very' bit.
'victory gained by effort' is the wordplay.
I cannot really understand how this works, but
'victory' could be 'win' (a win is a victory) and 'win' is present in the answer.
'effort' could be 'try' (synonyms) and 'try' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for wintry that I've seen before include "anything other than friendly?" , "Cold and icy" , "characteristic of one season" , "possibly cold and hostile" , "(Of weather) cheerless" .)