Speaker's shy in class (5)
I believe the answer is:
caste
'class' is the definition.
(type of social class)
'speaker's shy' is the wordplay.
'speaker's' shows a homophone (sound like).
'shy' becomes 'cast' (both can mean to throw).
'cast' sounds like 'CASTE'.
'in' is the link.
(Other definitions for caste that I've seen before include "A sect (anag)" , "Social status" , "Persons with class" , "Large, long-necked, wading bird" , "Social class or rank" .)