mostly preceded by 一?

[Scoobyqueen]

Is the idiomatic expression 咬牙 meaning "made up one's mind" preceded by 一?. I have seen it in the context of 所以一咬牙就买了 but I am not sure if 一 is not just part of the construction 一...就 rather than forming part of 咬牙.

How common is this word by the way?

[fengyixiao]

It is common.

To express "made up one's mind" with the idiom “咬牙”,you can say:

我一咬牙，买下了那双鞋子。 made up one's mind suddenly

一咬牙，我买下了那双鞋子。

咬一咬牙，我买下了那双鞋子。

我咬一咬牙，买下了那双鞋子。

咬咬牙，我买下了那双鞋子。 made up one's mind after think over

我咬咬牙，买下了那双鞋子。

Without "一"，“咬牙” will be used:

对那家伙，我恨得直咬牙。

对那家伙，我恨得是咬牙切齿。

[leeyah]

Here's also an example from advanced Chinese class (source: 《发展汉语》BLCUP) :

徘徊了足足十分钟之后，我还是咬咬牙走了进去。

Our teacher explained it as 坚定一下心情 (去做) & youdao dictionary translates it as "bite the bullet"