Concert lover spurning first impresario (8)
I believe the answer is:
promoter
'impresario' is the definition.
(I know that impresario can be written as promoter)
'concert lover spurning first' is the wordplay.
I cannot really understand how this works, but
'concert' could be 'prom' (abbreviation for promenade concert) and 'prom' is found within 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 promoter that I've seen before include "Boxing match organiser" , "One who stages boxing matches etc" , "Impresario" , "Advocate" , "One pushing" .)