Help with a Royal Opera House production perhaps (4)
I believe the answer is:
aida
'royal opera house production perhaps' is the definition.
(Aida is an opera)
'help with a' is the wordplay.
'help' becomes 'aid' (synonyms).
'with' means one lot of letters go next to another.
'aid'+'a'='AIDA'
(Other definitions for aida that I've seen before include "Covent Garden production?" , "Verdi opera" , "slave of Covent Garden" , "eponymous heroine" , "Fragrant shrub" .)