An impresario may do so without affectation (3,2,2,3)
I believe the answer is:
put on an act
'without affectation' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'an impresario may do' is the wordplay.
I cannot really see how this works, but
'an' could be 'a' and 'a' is located in the answer.
'do' could be 'act' (I've seen this in another clue) and 'act' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'so' acts as a link.
Can you help me to learn more?
(Other definitions for put on an act that I've seen before include "Pretend" , "Fake" .)