A sort of joke, possibly up north (3)
I believe the answer is:
pun
'a sort of joke' is the definition.
I can't judge whether this definition defines the answer.
'possibly up north' is the wordplay.
'possibly' indicates anagramming the letters.
'north' becomes 'N' (abbreviation).
'up' anagrammed gives 'pu'.
'pu'+'n'='PUN'
Can you help me to learn more?
(Other definitions for pun that I've seen before include "joke" , "Humorous play on words" , "A play on words, perhaps the lowest form of wit" , "A play on words - not the height of wit" , "Form of wordplay" .)