As used in making babies? (5)

I believe the answer is:

jelly

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'as' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

I can't explain the remainder of the clue.

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(Other definitions for jelly that I've seen before include "Wobbly sweet" , "Semi-solid food" , "Solid dessert" , "Gelatinous pudding" , "Wobbly pudding" .)

I've seen this clue in the Evening Standard.

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