Supplement to letter about bawdy puritans (6)
I believe the answer is:
prudes
'puritans' is the definition.
('prude' can be a synonym of 'puritan')
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for prudes that I've seen before include "People with exaggerated sense of propriety" , "Persons of exaggerated propriety, too easily shocked" , "They are easily shocked by matters relating to sex" , "They're excessively concerned about propriety and decorum" , "Stuffy types" .)