Hollywood actor's name in school plays (9)
I believe the answer is:
nicholson
'hollywood actor's' is the definition.
(actor Jack Nicholson)
'name in school plays' is the wordplay.
'name' becomes 'n' (common abbreviation e.g. on forms).
'plays' indicates an anagram.
'in'+'school'='inschool'
'inschool' with letters rearranged gives 'icholson'.
'n'+'icholson'='NICHOLSON'
(Other definitions for nicholson that I've seen before include "Jack -, US actor" , "See 8" , "Oscar winner 33" .)