Know beforehand (7)
I believe the answer is:
foresee
'know beforehand' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for foresee that I've seen before include "Be aware of beforehand" , "witness in advance?" , "Envisage" , "Realise or be aware of in advance" , "Expect" .)