Island-dwelling male put on nerd's body warmer (7)
I believe the answer is:
balmier
'body warmer' is the definition.
Both the answer and definition are comparative adjectives. Maybe you can see an association between them that I don't see?
'island-dwelling male put on nerd's' is the wordplay.
I cannot quite see how this works, but
'island' could be 'i' (geographical abbreviation) and 'i' is present in the answer.
an anagram of 'male' is 'alme' which is present in the remaining letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for balmier that I've seen is " (Of climate) more pleasantly warm".)