Opera pioneer — he abandons affected theatricals (9)
I believe the answer is:
scarlatti
'opera pioneer he abandons affected theatricals' is the definition.
The definition suggests a singular noun which matches the answer.
'opera pioneer he' is the wordplay.
I cannot quite understand how this works, but
'he' could be 'carl' and 'carl' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for scarlatti that I've seen before include "opera producer" , "Alessandro and Domenico --, Italian composers" , "Composer - trails cat (anag)" , "Cantatas by him?" , "Italian scoring" .)