Piano in old-time musical presentation (5)
I believe the answer is:
opera
'musical presentation' is the definition.
(I've seen this before)
'piano in old-time' is the wordplay.
'piano' becomes 'p' (musical abbreviation).
'in' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'time' becomes 'era' (era is a kind of time).
'o'+'era'='oera'
'p' going into 'oera' is 'OPERA'.
(Other definitions for opera that I've seen before include "Musical 11 across" , "Musical entertainment" , "Fidelio for instance" , "Musical piece accompanying a stage drama or comedy" , "Stage entertainment" .)