A giant, but getting progressively smaller? (4)

I believe the answer is:

ogre

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

'a giant' is the definition.
(ogre is a kind of giant)

'getting progressively smaller?' is the wordplay.
'OGRE' is hidden in amongst the letters.
But, I am uncertain how the hidden word is indicated.

'but' is the link.

Can you help me to learn more?

(Other definitions for ogre that I've seen before include "Jack's giant perhaps" , "Giant of folklore, eats humans" , "Fairy-tale creature" , "terrible person" , "One making giant strides" .)

I've seen this clue in the Evening Standard.

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