British school curriculum? It's very bitter! (4)
I believe the answer is:
brrr
'very bitter' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'british school curriculum?' is the wordplay.
'british' becomes 'br' (abbreviation for British).
'school curriculum?' becomes 'rr' (I can't explain this - if you can you should give a lot more credence to this answer).
'br'+'rr'='BRRR'
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for brrr that I've seen before include "I'm definitely not hot" , "Cold person's exclamation" , "How freezing" , "Indication of iciness" , "Complaint about cold" .)