Airdrie resident's more in need of liquid refreshment (5)
I believe the answer is:
drier
'need of liquid refreshment' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'airdrie resident's more in' is the wordplay.
'in' indicates the answer is hidden within the clue.
'DRIER' is hidden in the letters of 'airdrie residents more'.
(Other definitions for drier that I've seen before include "affected by sunnier climate" , "See 1" , "Less damp" , "Less wet" , "More withered" .)