Incurably overweight associate (7)
I believe the answer is:
fatally
'incurably' is the definition.
Both the answer and definition are adverbs. Maybe they are linked in a way I don't understand?
'overweight associate' is the wordplay.
'overweight' becomes 'fat' (similar in meaning).
'associate' becomes 'ally' (ally is a kind of associate).
'fat'+'ally'='FATALLY'
Can you help me to learn more?
(Other definitions for fatally that I've seen before include "in decisive manner" , "So as to cause death" , "Might one be wounded thus" , "producing disastrous result" , "with no hope of revival" .)