Duck with two functions? (5)
I believe the answer is:
douse
'duck' is the definition.
(synonyms)
'with two functions?' is the wordplay.
'two functions?' means two substitutions for 'function'.
'with' says to put letters next to each other.
'function' becomes 'do' (I've seen this in other clues).
'function' becomes 'use' (synonyms).
'do' put next to 'use' is 'DOUSE'.
(Other definitions for douse that I've seen before include "Put out (flame)" , "Extinguish (a fire)" , "can make you really wet" , "Drench; extinguish" , "snuff" .)