Cut reversed during solver's treatment (7)
I believe the answer is:
therapy
'treatment' is the definition.
(synonyms)
'cut reversed during solver's' is the wordplay.
'cut' becomes 'pare' (paring is a kind of cutting).
'reversed' shows that the letters should be reversed in order.
'during' means one lot of letters goes inside another.
'solver' becomes 'thy' (I've seen this in other clues).
'pare' in reverse letter order is 'erap'.
'erap' going into 'thy' is 'THERAPY'.
(Other definitions for therapy that I've seen before include "Remedial treatment" , "healing process" , "Relieving treatment" , "See 7" , "Curative treatment" .)