Dispatch in a sly way? (4)
I believe the answer is:
slay
'dispatch' is the definition.
(synonyms)
'a sly way?' is the wordplay.
'way?' indicates anagramming the letters (another way of arranging the letters).
'a'+'sly'='asly'
'asly' anagrammed gives 'SLAY'.
'in' acts as a link.
(Other definitions for slay that I've seen before include "Violently kill" , "Massacre" , "Destroy" , "Kill with premeditation" , "Kill (literary)" .)