A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

clean someone out • clean up on someone
clean someone out—(coll.) take everything from a person;
deprive or cheat smb. of his money, etc.: “She cleaned me
out,” says Williams. “She used me to get to America.”
clean up on someone —(U.S. coll.) defeat an opponent (in a
fight): Chavez looked tired and Tszyu cleaned up on him,
clocking him with a clean left hook and several right upper-
cuts.
clear a ship • clear a ship for action
clear a ship —pay the charges at the custom-house and re-
ceive permission to sail: The custom’s official told me that
only the captain could clear the ship and that I had to go back
and get him.
clear a ship for action —(also: clear the decks) remove all en-
cumbrances from the deck of a ship ready for an engagement:
Crews were often given a hot meal before being called to clear
the ship for action.
clear as crystal • clear as mud
clear as crystal —
1
. (of water, etc.) unclouded; transparent:
The cave was long and wide and pervaded by cold water, clear
as crystal. 2. (of a situation) very clear; easily understood: I
don’t know why you can’t understand the instructions — they’re
as clear as crystal to me.
Note: 
The expression does not fully correlate in meaning with
the phrase clear as a bell—
1
. (of sound) extremely clear: When
his daughter telephoned him from America he could hear her
as clear as a bell. 2. = clear as crystal 2: When I write some-
thing, the meaning is clear as a bell to me. When someone
reads what I wrote, the interpretation may be very different.
clear as mud —
1
. (joc.) = clear as crystal 2: It was clear as
mud that Angelides was very smart. But it was also clear that
he was not a politician…. 2. (ironic) not at all clear: I’m now
giving up as I’ve wasted too much time on this and the in-
structions are about as clear as mud.