Tight when holding court? It's the drink (6)
I believe the answer is:
nectar
'the drink' is the definition.
(nectar is a kind of drink)
'tight when holding court?' is the wordplay.
'tight' becomes 'near' (I've seen this in another clue).
'when holding' indicates putting letters inside.
'court?' becomes 'ct' (abbreviation used in road names).
'near' placed around 'ct' is 'NECTAR'.
'it's' acts as a link.
(Other definitions for nectar that I've seen before include "Honey of flowers - drink of the gods" , "Drink of gods and insects" , "Sweet fluid collected by bees" , "Sweet plant secretion" , "Sweet liquid of the gods" .)