Staring angrily at first person shouting on the phone (10)

I believe the answer is:

eyeballing

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'staring' is the definition.
The answer and definition can be both to do with perception as well as being present participle verbs.
Maybe you can see a link between them that I don't see?

I don't understand the remainder of the clue.

Can you help me to learn more?

I've seen this clue in The Independent.

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