Hen night lot? Too drunk, and old (4,2,3,5)
I believe the answer is:
long in the tooth
'old' is the definition.
(I've seen this before)
'hen night lot? too drunk' is the wordplay.
'drunk' indicates anagramming the letters.
'hen'+'night'+'lot'+'too'='hennightlottoo'
'hennightlottoo' anagrammed gives 'LONG IN THE TOOTH'.
'and' is the link.
(Other definitions for long in the tooth that I've seen before include "Rather old" , "Getting on a bit" , "indication of the need for cosmetic dentistry?" , "Are vampires so" , "Was a woolly mammoth" .)