String quartet's last to get drink (5)
I believe the answer is:
twine
'string' is the definition.
('twine' can be a synonym of 'string')
'quartet's last to get drink' is the wordplay.
'last' indicates one should take the final letters.
'to get' says to put letters next to each other.
'drink' becomes 'wine' (wine is a kind of drink**).
The final letter of 'quartet' is 't'.
't'+'wine'='TWINE'
(Other definitions for twine that I've seen before include "twist" , "Tough string" , "wind" , "Garden string" , "Interweave" .)