State of watering hole in antiquity (8)
I believe the answer is:
republic
'state' is the definition.
(I've seen this before)
'watering hole in antiquity' is the wordplay.
'watering hole' becomes 'pub' (I've seen this in another clue).
'in' is an insertion indicator.
'antiquity' becomes 'relic' (relic is a kind of antiquity).
'pub' placed within 'relic' is 'REPUBLIC'.
'of' acts as a link.
(Other definitions for republic that I've seen before include "Type of state" , "State without monarch" , "State in which the people hold the power" , "Country with no king" , "The political system is an epic blur" .)