Giving cheer, Scooby-Doo gleefully lifted masks (8)

I believe the answer is:

feelgood

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

'lifted masks' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'giving cheer scooby-doo gleefully' is the wordplay.
'FEELGOOD' is hidden back-to-front in amongst the letters.
However, I am unsure how the hidden word is indicated.

Can you help me to learn more?

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