do a bit

do a bit

1. To do only a small amount of something. I was only able to do a bit of cleaning before your mother called—that's why the dirty dishes are still on the table. A: "Did you write your essay?" B: "I did a bit, but I decided to take a break.
2. To tell a joke or perform a short comic routine, especially when done in a satirically serious or sincere manner. The comic has such a dry sense of humor that it can sometimes be hard to tell when he's doing a bit or actually being serious.
See also: bit

do (one's) bit

To make an individual contribution toward an overall effort.
See also: bit
References in classic literature ?
And that's reasonable; for if Old Harry's a mind to do a bit o' kindness for a holiday, like, who's got anything against it?
"My education has always been a big deal to me and my two sisters were naturally clever and passed with flying colours - but I needed to do a bit more revision.