Chubby person hoped norm would change (9)
I believe the answer is:
endomorph
'chubby person' is the definition.
The definition suggests a singular noun which matches the answer.
'hoped norm would change' is the wordplay.
'hoped norm' can be anagrammed to 'ENDOMORPH'.
Though, I'm not clear how this is indicated.
Can you help me to learn more?
(Other definitions for endomorph that I've seen before include "Heavy person" , "Stocky person" , "fattish figure" , "Portly sort" , "Fatty type" .)