Wine made from a resin, drunk round Thessaly's capital (7)
I believe the answer is:
retsina
'wine' is the definition.
(retsina is a kind of wine)
'a resin drunk round thessaly's capital' is the wordplay.
'drunk' indicates anagramming the letters.
'round' indicates putting letters inside.
'capital' indicates taking the first letters.
The first letter of 'thessaly' is 't'.
'a'+'resin'='aresin'
'aresin' is an anagram of 'resina'.
'resina' going around 't' is 'RETSINA'.
'made from' is the link.
(Other definitions for retsina that I've seen before include "Greek white wine flavoured with resin" , "Nastier (anag) - Greek wine" , "Type of Greek wine" , "Greek wine - nastier sort" , "Flavoured Greek white wine - nastier brand" .)