Doctor loves catching European opera (9)
I believe the answer is:
rigoletto
'opera' is the definition.
(I know that Rigoletto is a opera)
'doctor loves catching european' is the wordplay.
'doctor' becomes 'rig' (both can mean to forge or manipulate).
'loves' becomes 'oo' (two O's - 'love' means zero in tennis).
'catching' is an insertion indicator.
'european' becomes 'Lett' (old-fashioned term for someone from Latvia).
'oo' placed around 'lett' is 'oletto'.
'rig'+'oletto'='RIGOLETTO'
(Other definitions for rigoletto that I've seen before include "noted work" , "titled man" , "Opera by Verdi" , "court favourite" , "Verdi's hunchback jester" .)