Setter and setter drinking drink and drink (6)
I believe the answer is:
imbibe
'drink' is the definition.
('imbibe' can be a synonym of 'drink')
'setter and setter drinking drink' is the wordplay.
'setter' becomes 'i' (the person that set the crossword).
'and' is a charade indicator (letters next to each other).
'setter' becomes 'me' (the setter of the clue).
'drinking' means one lot of letters goes inside another.
'drink' becomes 'bib' (bibbing is a kind of drinking**).
'me' enclosing 'bib' is 'mbibe'.
'i'+'mbibe'='IMBIBE'
'and' is the link.
(Other definitions for imbibe that I've seen before include "Take in (with one's mother's milk?)" , "Drink or absorb into mind" , "Drink in - assimilate" , "Drink, take in" , "Partake of drink" .)