Also, have a line on. Acquire information about something or someone, come to know. For example, Sue got a line on some possible tennis partners, or The realtor has a line on a number of vacant apartments. Similarly, give someone a line on means “provide information about,” as in The librarian gave me a line on the books I would need. This idiom uses line in the sense of “a direct course.” [c. 1900] Also see get a fix on.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.