Reserved for the cast (3)
I believe the answer is:
shy
I believe this is a double definition.
'reserved' is the first definition.
(I've seen this in another clue)
'the cast' is the second definition.
(both can mean to throw or fling)
'for' is the link.
(Other definitions for shy that I've seen before include "Coy" , "Fling or throw" , "Timid (around people)" , "Timid and self-conscious" , "Nervous with others" .)