Star part, so got in cast (11)
I believe the answer is:
protagonist
'star' is the definition.
(thesaurus)
'part so got in cast' is the wordplay.
'cast' indicates anagramming the letters.
'part'+'so'+'got'+'in'='partsogotin'
'partsogotin' anagrammed gives 'PROTAGONIST'.
(Other definitions for protagonist that I've seen before include "Leading player" , "champion" , "Lead character" , "Key character in a novel" , "Leading character in a play, novel, etc" .)