Endless complaint about one supporting account? I am surprised! (8)

I believe the answer is:

gracious

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

'i am surprised' is the definition.
('gracious' may be said in surprise)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for gracious that I've seen before include "Royal epithet" , "Affable, courteous, kindly" , "Elegant - polite" , "Courteous, kind, pleasant" , "alternative to exclamation of grief?" .)

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