Urchin and fish served up with a cake (10)
I believe the answer is:
ragamuffin
'urchin' is the definition.
(I've seen this before)
'up with a cake' is the wordplay.
'up with' becomes 'rag' (I can't explain this - if you can you should give a lot more credence to this answer).
'cake' becomes 'muffin' (I've seen this before).
'rag'+'a'+'muffin'='RAGAMUFFIN'
'and fish served' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for ragamuffin that I've seen before include "little scruff" , "Fuming afar (anag)" , "Scruffy little fellow" , "Scruffy urchin" , "One got up badly" .)