That’s amazing! (3)
(Other definitions for gee that I've seen before include "Alphabet's seventh letter" , "Urge horse - expression of surprise" , "Gracious" , "Expression of mild surprise (mainly US)" , "Golly" .)
(Other definitions for wow that I've seen before include "Expression of amazement" , "Exclamation of admiration - another palindrome" , "Expression of great admiration" , "boy" , "Palindromic exclamation of surprise or admiration" .)
'that's amazing' is the definition.
(expression of surprise)
This is all the clue.