Thankless young rate fulfilment as less edgy (10)

I believe the answer is:

ungrateful

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

'thankless' is the definition.
(similar in meaning)

'young rate fulfilment as less edgy' is the wordplay.
'UNGRATEFUL' is hidden within the letters.
But, I'm not sure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for ungrateful that I've seen before include "Thankless" , "no thanks" , "Disagreeable" .)

I've seen this clue in the Sydney Morning Herald.

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