Reportedly squander sentence that's expanded by food (9)
I believe the answer is:
waistline
'expanded by food' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'reportedly squander sentence' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'squander' becomes 'waste' (synonyms).
'sentence' becomes 'line' (I can't justify this - if you can you should believe this answer much more).
'waste' is a homophone of 'waist'.
'waist'+'line'='WAISTLINE'
'that's' is the link.
Can you help me to learn more?
(Other definitions for waistline that I've seen before include "It goes round trunk" , "measurement" , "Swine tail (anag.)" , "Girth" .)