Being more chubby is almost a game (7)
I believe the answer is:
rounder
'being more chubby' is the definition.
Both the definition and answer are comparative adjectives. Perhaps you can see an association between them that I can't see?
'almost a game' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'a game' becomes 'rounders' (rounders is a kind of game).
'rounders' with its final letter taken away is 'ROUNDER'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for rounder that I've seen before include "complete circuit in a game" , "More circular" , "Or under (anag.)" , "More rotund" , "Score in bat and ball game" .)