Unlimited wine for chap in Cologne? (4)
I believe the answer is:
herr
'chap in cologne?' is the definition.
(German equivalent of 'Mr')
'unlimited wine' is the wordplay.
'unlimited' says to take the centre (discard the edges or 'limits' of the word).
'wine' becomes 'sherry' (sherry is a kind of wine).
The centre of 'sherry' is 'HERR'.
'for' acts as a link.
(Other definitions for herr that I've seen before include "Dieter respectfully addressed" , "Mister in German" , "German man's title" , "European guy" , "Form of address for German male" .)