Oscar being claimed by one down grated with a late screen star (7,4)

'screen star' is the definition.
(actress Natalie Wood, 1938-1981)

'oscar being claimed by one down grated with a late' is the wordplay.
I cannot really see how this works, but
'oscar' could be 'o' (phonetic alphabet: alpha, bravo, charlie etc.) and 'o' is located in the answer.
'by' could be 'at' and 'at' is present in the answer.
'one' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
'down' could be 'd' and 'd' is found in the answer.
'with' could be 'w' (abbreviation) and 'w' is found in the answer.
'a' is found in the answer.
This explanation may well be incorrect...