One antonym for clumsy is graceful.
Gloomy and glum are the opposite of cheerful. They begin with the letter G.
Given
The opposite of "bright" is usually "dim." The "g" may be incorrect.
Glut
A four letter word that is opposite of received and starts with the letter g is gave.
A song starting with the letter G is Van Morrison's 'Gloria!'.
A thing starting with G is garage.
An antelope starting with G is gazelle.
A musical instrument starting with the letter g is a guitar.
The three-letter opposite of cold is "hot." I realize that doesn't end in "g."
A place starting with G is Great Britain.
A beverage starting with the letter "g" can be Gatorade... or if you found another answer, then great.