It’s a closed book

closed shop

closed book

Closed!

on closer examination

Closing down sale!

closing of the shooting season

clot

Clothes make the man

Clothes make people.

clothes hung out to dry

to be on cloud nine

to cloud the issue

I'm on cloud nine at the moment.

on cloud nine

clouds on the horizon

It's cloudy.

to clown about

to go clubbing

to clue someone/oneself up

to be clued up

to be clued up on something

to be clueless

clumsy fingers

clumsy fool