Consider muscle in relaxed state (7)
I believe the answer is:
respect
'consider' is the definition.
(respecting is a kind of considering)
'muscle in relaxed state' is the wordplay.
'muscle' becomes 'pec' (I've seen this in other clues).
'in' is an insertion indicator.
'relaxed state' becomes 'rest'.
'pec' placed inside 'rest' is 'RESPECT'.
(Other definitions for respect that I've seen before include "Appreciate - courtesy" , "Appreciate - consideration" , "Admiration or esteem" , "Admire, think highly of" , "'Regard, esteem (7)'" .)