"I am sick of looking at the clock. " could this work also ?
Perhaps "I am sick and tired ...", surely not "sick" alone. "Stanco" is more "tired" than "fed up"
word reference shows stanco as an adjective can mean
bored, fed up, bothered
as well as
tired, fatigued, weary
although it appears fed up is figurative
Why not ... sto stanco di guardando al'orologio???
I don't know if "clock-watching" is a purely British idiom, but that is how we would probably phrase this over here. It was rejected nevertheless. Reported 24th February 19
Watching the clock and looking at the clock are different things.