Letter that’s awesome or disappointing (3)

I believe the answer is:

gee

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'letter' is the definition.
(G)

I don't understand the rest of the clue.

(Other definitions for gee that I've seen before include "7th letter" , "Mild expression of surprise, may go before whiz" , "Gracious" , "Alphabet's seventh letter" , "Wow!" .)

I've seen this clue in The Times.

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