Player one in Dickensian musical (7)
I believe the answer is:
olivier
'player' is the definition.
(I know that Olivier is an player)
'one in dickensian musical' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' is an insertion indicator.
'dickensian musical' becomes 'oliver' (I've seen this before).
'i' inserted inside 'oliver' is 'OLIVIER'.
(Other definitions for olivier that I've seen before include "N Messiaen, French composer" , "Classical actor" , "Laurence --, first actor to be made a life peer" , "English actor, first artistic director of the National Theatre" , "O! Virile (anag) - English actor, d. 1989" .)