Drink large rum (5)
I believe the answer is:
lager
'drink' is the definition.
(lager is a kind of drink)
'large rum' is the wordplay.
'rum' indicates an anagram (rum can mean strange or unusual).
'large' anagrammed gives 'LAGER'.
(Other definitions for lager that I've seen before include "Regal (anag) - drink" , "Light-coloured beer" , "Lout's drink?" , "Local offering" , "Regal sort of beer" .)