Jokes about RI volunteers and prudes (8)
I believe the answer is:
'prudes' is the definition.
('puritan' can be a synonym of 'prude')
'jokes about ri volunteers' is the wordplay.
'jokes' becomes 'puns' (punning is a kind of joking).
'about' indicates putting letters inside.
'volunteers' becomes 'TA' (abbreviation for Territorial Army).
'puns' enclosing 'rita' is 'PURITANS'.
'and' is the link.
(Other definitions for puritans that I've seen before include "Stern religious people like Rasputin" , "Strictly religious people like Rasputin" , "Killjoys, prudes" .)