Second of two drinks (7)
I believe the answer is:
support
'second' is the definition.
(I've seen this before)
'two drinks' is the wordplay.
'two drinks' can mean two substitutions for 'drink'.
'drink' becomes 'sup' (to sup is to drink).
'drink' becomes 'port' (port is a kind of drink).
'sup'+'port'='SUPPORT'
'of' is the link.
(Other definitions for support that I've seen before include "Shore up" , "Bolster or back up" , "base" , "Provide with food, clothing and shelter, or encouragement" , "used to give strength?" .)