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

have an eye out for someone • have eyes for
 someone
have an eye out for someone —be very alert wishing to pick
out one particular person: When she was out back having a
smoke … she had an eye out for him.
have eyes for someone —(coll.) have a strong romantic interest
in a person: Now, my sister was a beautiful girl and I knew
even Mitchell had eyes for her.
have an idea • have ideas
have an idea —
1
. have a notion of smth.: We had an idea of
a law firm that tossed out the usual law firm trappings: no
mahogany or marble; no suits unless that’s what you prefer to
wear. 2. think or suppose smth.: I heard what he said to you.
I had an idea you weren’t going to take it lying down.
have ideas —entertain undesirable or harmful notions: That’s
the second happy couple I’ve seen busted up and it’s cured me
if I ever had ideas. I’d no more marry with a war on than jump
over the moon.
have an in • have an out
have an in —(coll.) have influence with smb. of authority:
Sorry, I don’t have an in, but I know someone who does.
have an out—(coll.) have a means of escape or avoiding
smth.: No matter what happens, he always has an out.
have an in with someone • have it in for someone
have an in with someone—(coll.) have influence with smb.
of authority: He had an in with the city government, but that
doesn’t mean they knew everything he did.
Note: 
The expression does not correlate in meaning with the
phrase have a run-in with someone—(coll.) have a troublesome
encounter or a row with a person: Your father and I have many
run-ins these days. He can’t get it into his thick skull that I
have come of age.
have it in for someone —show ill will towards smb.; intend
to do harm to a person: I just don’t want to lose my funding
because she has it in for me badmouthing me to everyone in
the department.
See also: be in with someone / be with someone.