do/try your level best

do (one's) level best

To do as well as one can at something. I'm just not good at math, so, believe me, a B- in Algebra means that I've done my level best. No, you're not the star player on the team, but you always do your level best, which encourages the rest of us to do the same.
See also: level

try (one's) level best

To try as hard as one can; to try one's best. I'm just not good at math, so believe me, a B- in Algebra means that I've tried my level best. No, you're not the star player on the team, but you always try your level best, which encourages the rest of us to do the same.
See also: level, try
Farlex Dictionary of Idioms.

do your level best

COMMON If you do your level best to do something, you try as hard as you can to do it. The President told American troops that he would do his level best to bring them home soon. They're doing their level best to answer all the questions that people have.
See also: level
Collins COBUILD Idioms Dictionary, 3rd ed.

do your level best

do your utmost; make all possible efforts.
See also: level
Farlex Partner Idioms Dictionary

do/try your level ˈbest (to do something)

try as hard as you can: I’ll do my level best to be there by ten o’clock, but I can’t promise anything.
See also: level, try
Farlex Partner Idioms Dictionary
See also:
  • (I) hope not
  • hope not
  • not by any means
  • by no means
  • not for a second
  • iota
  • not an iota
  • not for a minute
  • not for a moment
  • ain't