Drink very quietly overlooking old city (6)
I believe the answer is:
aleppo
'city' is the definition.
(Aleppo is an example)
'drink very quietly overlooking old' is the wordplay.
'drink' becomes 'ale' (type of beer).
'very quietly' becomes 'pp' (musical abbreviation for pianissimo).
'overlooking' means one lot of letters go next to another (in a down clue, some letters go above others).
'old' becomes 'o' (abbreviation).
'ale'+'pp'+'o'='ALEPPO'
(Other definitions for aleppo that I've seen before include "Middle East city" , "Ancient city, in Syria" , "City in Syria - lop ape (anag)" , "Largest city in Syria before the massive damage of the civil war" , "War-torn city of Syria" .)