le la...???

[Clare H]

I have a sentence that I am having trouble with translating, can anyone help?

'Quel que soit le denouement de l'histoire, ce coup de theatre aura un contrechoc, il donnera le la a un eveil de la subversion'

The problem is with the part 'le la'... 'la' is in italics in the book, and does NOT have an accent, so I guess can't mean 'there' - but no idea what it does mean. The sentence is from a novel, and the speaker is a woman who is taking part in a civil revolt, if that is any help...

Thanks for any suggestions!!

[Erwan]

Here la  is not the article but a musical note.  Donner le la means set the tone.

[Clare H]

Ah! Merci! I could not find this idiom anywhere