Second drinker has a fund (5)
I believe the answer is:
slush
'a fund' is the definition.
(slush fund is a kind of fund)
'second drinker' is the wordplay.
'second' becomes 's' (common abbreviation**).
'drinker' becomes 'lush' (lush is a kind of drinker).
's'+'lush'='SLUSH'
'has' is the link.
(Other definitions for slush that I've seen before include "sentimentality" , "that has been frozen" , "Partly melted snow" , "Kind of fund" , "emotionalism" .)