In need of a drink, GP maybe ending in distillery (3)
I believe the answer is:
dry
'in need of a drink' is the definition.
'gp maybe ending in distillery' is the wordplay.
'gp maybe' becomes 'dr' (general practitioner).
'ending in' says to take the final letters.
The last letter of 'distillery' is 'y'.
'dr'+'y'='DRY'
(Other definitions for dry that I've seen before include "Having given up drinking" , "Without moisture" , "Formal" , "Waterless" , "Sardonic" .)