Concoction (4)
I believe the answer is:
brew
'concoction' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for brew that I've seen before include "Prepare (drink of tea)" , "Infuse" , "Ferment, concoct" , "Ferment rather than distil" , "Infusion" .)