Prudish person (4)
I believe the answer is:
prig
'prudish person' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for prig that I've seen before include "Smug type" , "Smug hypocrite" , "Sanctimonious person" , "Smugly self-righteous person" , "Over-fussy and self-righteous type" .)