Spot reserved initially for prophet (4)
I believe the answer is:
seer
'for prophet' is the definition.
(both can mean someone who tells the future)
'spot reserved initially' is the wordplay.
'spot' becomes 'see' (both can mean to notice or observe).
'initially' says to take the initial letters.
The initial letter of 'reserved' is 'r'.
'see'+'r'='SEER'
(Other definitions for seer that I've seen before include "Regard with respect" , "Person who can read the future" , "I envisage" , "One divines the future" , "One has unusual foresight" .)