Spanish gentleman’s sister taking in opera company (5)
I believe the answer is:
senor
'spanish gentleman's' is the definition.
(Spanish equivalent to 'mister')
'sister taking in opera company' is the wordplay.
'sister' becomes 'sr' (abbreviation as in names of nuns).
'taking in' means one lot of letters goes inside another.
'opera company' becomes 'ENO' (English National Opera).
'sr' placed around 'eno' is 'SENOR'.
(Other definitions for senor that I've seen before include "Mister in European country" , "'Mister' in Spain" , "Snore like Spanish gent" , "A Spanish mister" , "Snore (anag.)" .)