Presage what the sun will cause in front (10)
I believe the answer is:
foreshadow
'presage' is the definition.
(I know that presage can be written as foreshadow)
'the sun will cause in front' is the wordplay.
I cannot quite see how this works, but
'sun' could be 's' (abbreviation) and 's' is found in the answer.
'front' could be 'fore' (fore is a kind of front) and 'fore' is located in the answer.
This explanation may well be incorrect...
'what' acts as a link.
Can you help me to learn more?
(Other definitions for foreshadow that I've seen before include "Warn" , "Give warning" , "Presage" .)