Forecast version of Grease, after poor start (7)
I believe the answer is:
presage
'forecast' is the definition.
(I know that forecast can be written as presage)
'version of grease after poor start' is the wordplay.
'version of' is an anagram indicator.
'after' means one lot of letters go next to another.
'start' suggests taking the first letters.
The first letter of 'poor' is 'p'.
'grease' is an anagram of 'resage'.
'resage' put after 'p' is 'PRESAGE'.
(Other definitions for presage that I've seen before include "Be a sign or warning of (an event)" , "Forecast, foreshadow" , "Be an advance sign of, portend" , "Foretell" , "Be a sign of (something)" .)