Relaxed about muscle being admired (9)
I believe the answer is:
respected
'being admired' is the definition.
(thesaurus)
'relaxed about muscle' is the wordplay.
'relaxed' becomes 'rested' (I've seen this before).
'about' means one lot of letters goes inside another.
'muscle' becomes 'pec' (I've seen this in other clues).
'rested' placed around 'pec' is 'RESPECTED'.
(Other definitions for respected that I've seen before include "Held in esteem" , "Looked up to" , "Had a high regard for someone" , "Regarded highly" , "Held in high regard" .)