have a down on someone/something

have a down on (someone or something)

To have or express negative or overly critical feelings toward someone or something. I don't know why you have a down on Robert—he's such a nice guy to everyone! Don't have a down on this vacation to your grandparents' farm. I know it's not very exotic, but we'll still have a great time!
See also: down, have, on
Farlex Dictionary of Idioms.

have a down on someone/something

or

have a downer on someone/something

BRITISH
If you have a down on someone or something or you have a downer on them, you do not like them or you disapprove of them. Snobs would have a down on a man with a south London accent. For some reason Jackie has always had a downer on me.
See also: down, have, on, someone, something
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • be down on (someone or something)
  • a hard head
  • pixel peeper
  • buddy up
  • bring (one) back to reality
  • bring back to reality
  • have (one's)/a beady eye on (someone or something)
  • keep (one's)/a beady eye on (someone or something)
  • keep a beady eye on somebody/something
  • big bully