Crossword Genius

One of vital cosmetics (4)

Ross

I believe the answer is:

talc

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

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

'of vital cosmetics' is the wordplay.
'of' indicates a hidden word.
'TALC' is hidden in the letters of 'vital cosmetics'.

Can you help me to learn more?

(Other definitions for talc that I've seen before include "Softest mineral on Mohs hardness scale" , "(Mineral providing) powder" , "Powder used as toiletry" , "soother" , "I may dust" .)

I've seen this clue in The Daily Express and The Mirror.
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