Note model is overweight? (3)
I believe the answer is:
fat
'is overweight?' is the definition.
(similar in meaning)
'note model' is the wordplay.
'note' becomes 'fa' (fourth note in sol-fa notation: doh, ray, me...).
'model' becomes 't' (Ford Model T car).
'fa'+'t'='FAT'
(Other definitions for fat that I've seen before include "Adipose tissue" , "Greasy substance" , "Overweight, stout" , "Cooking grease" , "eg Lard" .)