Seed rating announced (5)

I believe the answer is:

semen

I'm a little stuck... Click here to teach me more about this clue!

'seed' is the definition.
(I know that seed can be written as semen)

I don't understand the remainder of the clue.

(Another definition for semen that I've seen is " Liquid carrying spermatozoa".)

I've seen this clue in The Independent.

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