Appreciative given this much fuel? (8)

I believe the answer is:

grateful

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

I cannot understand how the remainder of the clue works.

(Other definitions for grateful that I've seen before include "Showing appreciation for kindness" , "Beholden" , "Thankful, appreciative" , "Showing thankfulness" , "Felt a rug (anag)" .)

I've seen this clue in The Sun.

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