keep in line is a verb meaning "maintain influence over (others or oneself) skillfully, usually to one's advantage". It carries one recorded sense.
maintain influence over (others or oneself) skillfully, usually to one's advantage
“She manipulates her boss”
“She is a very controlling mother and doesn't let her children grow up”
“The teacher knew how to keep the class in line”
“she keeps in line”
Definitions, synonyms and semantic relations for keep in line come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.