Fool around with poem in Ukrainian city (6)
I believe the answer is:
odessa
'ukrainian city' is the definition.
(I've seen this before)
'fool around with poem' is the wordplay.
'fool' becomes 'ass' (both can mean a stupid person).
'around' is a reversal indicator.
'with' is a charade indicator (letters next to each other).
'poem' becomes 'ode' (ode is a kind of poem).
'ass' written backwards gives 'ssa'.
'ssa' after 'ode' is 'ODESSA'.
'in' acts as a link.
(Other definitions for odessa that I've seen before include "Ukrainian naval base" , "Seaport" , "Battleship Potemkin mutiny port" , "Do seas come into Ukrainian city?" , "Port city on the Black Sea" .)