Danish city, second to Copenhagen, not spread out (6)
I believe the answer is:
odense
'danish city' is the definition.
(I've seen this before)
'second to copenhagen not spread out' is the wordplay.
I cannot really understand how this works, but
'second' could be 's' (common abbreviation) and 's' is located in the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
The remaining letters 'dene' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for odense that I've seen before include "Danish city" , "where Canute founded a cathedral" , "Foreign city" , "foreign port?" , "in Denmark?" .)