What does " have a go" mean?

[japanjapan]

Dear teachers,

Please look at the following paragraph:

In this, as at other such events, a striking sociological pattern was evident. Most “have-a-go heroes” were, like Mr Henrique, young, male and foreign.

The article is about fighting against criminals, native Britons are not so brave as foreigners, such foreigners are call heroes.

Thanks

[Tdol]

A 'have-a-go hero' is one who confrants danger, usually against the odds; chasing an robber, etc.