This can cause laughter or tears (3)

I believe the answer is:

gas

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'tears' is the definition.
The definition and answer can be both acts as well as being plural nouns.
Maybe they are linked in a way I don't understand?

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for gas that I've seen before include "eg Helium" , "Form of fossil fuel" , "It's not liquid or solid, like American petrol" , "Possibly noble" , "Chat (colloq.)" .)

I've seen this clue in The Irish Independent.

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