Before wise man reveals foreboding (7)
I believe the answer is:
presage
'foreboding' is the definition.
('presage' can be a synonym of 'foreboding')
'before wise man' is the wordplay.
'before' becomes 'pre'.
'wise man' becomes 'sage' (sage is a kind of wise man**).
'pre'+'sage'='PRESAGE'
'reveals' is the link.
(Other definitions for presage that I've seen before include "Forecast, foreshadow" , "Be a sign of (something)" , "Foretell" , "Be an advance sign of, portend" , "Be a sign or warning of (an event)" .)