Drury Lane Theatre composer (4)
I believe the answer is:
arne
'drury lane theatre composer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for arne that I've seen before include "Rule Britannia composer, d. 1778" , "Rule, Britannia author" , "Rule Britannia's composer, d. 1778" , "Thomas --, composer of Rule, Britannia!" .)