From Longman Dictionary of Contemporary Englishbe in somebody’s linebe in somebody’s lineinformalINTERESTED to be the type of thing that someone is interested in or good at Acting’s not really in my line, I’m afraid. → line
Examples from the Corpus
be in somebody’s line• He was in a line of three cars.• The name is in the first field because it is in the first line. 8.• My father thinks they should be in curved lines.• Do not put fluffy rugs in front of open fires, where they are in the direct line of sparks.• They were in a straight line but when Boris clapped his paws they began to march.• This is in fact the line which Berger then developed.• The Law Society too was in the firing line. 