Have a drink up in Italian city (4)
I believe the answer is:
pisa
'italian city' is the definition.
(city in Italy)
'have a drink up' is the wordplay.
'have' becomes 'a' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a drink' becomes 'sip' (I've seen this before).
'up' is a reversal indicator (in down clue: letters go upwards).
'a'+'sip'='asip'
'asip' back-to-front is 'PISA'.
'in' is the link.
Can you help me to learn more?
(Other definitions for pisa that I've seen before include "City on the River Arno" , "much-visited city" , "Site of the famous leaning tower" , "Location of leaning tower" , "Italian city with famous tower" .)