Appreciative given this much fuel? (8)
I believe the answer is:
'appreciative' is the definition.
(similar in meaning)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for grateful that I've seen before include "Showing appreciation for kindness" , "Beholden" , "Thankful, appreciative" , "Showing thankfulness" , "Felt a rug (anag)" .)