Gasp about restraint for one being treated (7)
I believe the answer is:
patient
'one being treated' is the definition.
(I've seen this before)
'gasp about restraint' is the wordplay.
'gasp' becomes 'pant' ('pant' can be a synonym of 'gasp').
'about' is an insertion indicator.
'restraint' becomes 'tie' (I've seen this before).
'pant' enclosing 'tie' is 'PATIENT'.
'for' is the link.
(Other definitions for patient that I've seen before include "Calm" , "Doctor's visitor; composed" , "Doctor's 'customer'" , "One being treated" , "One receiving medical care" .)