More muscular appearance initially feeds one's strength (7)
I believe the answer is:
meatier
'more muscular' is the definition.
Both the definition and answer are comparative adjectives. Perhaps they are linked in a way I don't understand?
'appearance initially feeds one's strength' is the wordplay.
'initially' suggests taking the first letters.
'feeds' indicates putting letters inside (one word is fed by another set of letters).
'one' becomes 'me' (a setter might use 'one' to humourously mean 'me').
'strength' becomes 'tier' (I am not sure about this - if you are sure you should believe this answer much more).
The first letter of 'appearance' is 'a'.
'me'+'tier'='metier'
'a' inserted inside 'metier' is 'MEATIER'.
Can you help me to learn more?
(Other definitions for meatier that I've seen before include "having more muscle" , "More brawny" , "Having more flesh" , "More substantial - emirate (anag)" .)