Not very hot, but nevertheless approved of (4)
I believe the answer is:
cool
'not very hot' is the definition.
'cool' can be an answer for 'hot' (thesaurus). I am unsure of the 'not very' bit.
'nevertheless approved of' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is present in the answer.
The remaining letters 'col' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'but' acts as a link.
Can you help me to learn more?
(Other definitions for cool that I've seen before include "Fashionably attractive" , "Quite cold" , "Fan" , "Not keen!" , "chic" .)