Excellent reserve embracing exercise? Right (6)
I believe the answer is:
superb
'excellent' is the definition.
(thesaurus)
'reserve embracing exercise? right' is the wordplay.
'reserve' becomes 'sub' (I've seen this in other clues).
'embracing' indicates putting letters inside.
'exercise?' becomes 'pe' (Physical Education).
'right' becomes 'r' (common abbreviation).
'pe'+'r'='per'
'sub' placed around 'per' is 'SUPERB'.
(Other definitions for superb that I've seen before include "Gorgeous" , "Triumphantly effective" , "fine" , "Splendid, marvellous" , "'Excellent, brilliant (6)'" .)