It's a fine point on a drawing, perhaps (3)
I believe the answer is:
pin
'a drawing perhaps' is the definition.
I can't judge whether this definition defines the answer.
'it's a fine point on' is the wordplay.
'it's a fine' becomes 'pi' (I can't explain this - if you can you should believe this answer much more).
'point' becomes 'n' (North).
'on' says to put letters next to each other.
'pi'+'n'='PIN'
Can you help me to learn more?
(Other definitions for pin that I've seen before include "Secure" , "Flagged stick placed in golf hole" , "Peg or nail" , "form of identification" , "Fasten; a security code" .)