Take a muffin from an urchin, just to tease (3)
I believe the answer is:
rag
'to tease' is the definition.
('rag' can be a synonym of 'tease')
'take a muffin from an urchin' is the wordplay.
'take' becomes 'r' (abbreviation for 'recipe', Latin for 'take').
'a muffin from an urchin' becomes 'ag' (I can't justify this - if you can you should believe this answer much more).
'r'+'ag'='RAG'
'just' is the link.
Can you help me to learn more?
(Other definitions for rag that I've seen before include "Ridicule" , "Scrap of old cloth" , "Student fundraiser" , "Small piece of cloth and university week" , "Disreputable paper" .)