Up for one small television acting role – initially one might expect better (4,4)
I believe the answer is:
film star
'one might expect better' is the definition.
I can't tell whether this defines the answer.
'up for one small television acting role initially' is the wordplay.
'up for' becomes 'film' (I can't explain this - if you can you should give a lot more credence to this answer).
'one small' becomes 's' (abbreviation - e.g. clothes size).
'initially' suggests taking the first letters.
The first letters of 'television acting role' is 'tar'.
'film'+'s'+'tar'='FILM-STAR'
Can you help me to learn more?
(Other definitions for film star that I've seen before include "Hollywood notable" , "Hollywood hero?" , "Ma flirts with Hollywood idol" , "Famous movie actor" , "Cinema celebrity" .)