Old theatre recalled a musical work (5)
I believe the answer is:
opera
'musical work' is the definition.
(I've seen this before)
'old theatre recalled a' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'theatre' becomes 'rep' (I've seen this in other clues).
'recalled' is a reversal indicator.
'rep' written backwards gives 'per'.
'o'+'per'+'a'='OPERA'
(Other definitions for opera that I've seen before include "Musical in which all the words are sung" , "Billy Budd, for instance" , "Musical extravaganza" , "Patience, perhaps" , "Eg, Carmen" .)