Grace shown by opener bagging a couple of fifties (5)
I believe the answer is:
kelly
'grace' is the definition.
(actress Grace Kelly)
'opener bagging a couple of fifties' is the wordplay.
'opener' becomes 'key' (keys open things).
'bagging' is an insertion indicator (I've seen this in other clues).
'a couple of fifties' becomes 'LL' (L is the Roman numeral for fifty).
'key' placed around 'll' is 'KELLY'.
'shown by' is the link.
(Other definitions for kelly that I've seen before include "Grace --, US actress who married a prince" , "- - Sotherton, athlete" , "Ned ---, Aus. outlaw" , "- - Holmes, Olympic athlete" , "Gene - - , star of Singin' In The Rain" .)