Locate part of muscle, taut: issue's back (7)
I believe the answer is:
situate
'locate' is the definition.
('situate' can be a synonym of 'locate')
'part of muscle taut issue's back' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'back' says the letters should be written in reverse.
'etautis' can be found hidden inside 'muscle taut issues'.
'etautis' in reverse letter order is 'SITUATE'.
(Other definitions for situate that I've seen before include "station" , "put in context" , "Place in a particular location" , "Locate" , "Position" .)