Rather cheeky, which is not so hot (7)
I believe the answer is:
coolish
'hot' is the definition.
Both the definition and answer are adjectives.
Maybe they are linked in a way I don't understand?
'rather cheeky which is not' is the wordplay.
I cannot really see how this works, but
'is' is present in the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'so' is the link.
Can you help me to learn more?
(Another definition for coolish that I've seen is " Rather unfriendly".)