Cast directives neglected TV shows - Glow or Shine? (8)

I believe the answer is:

iridesce

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'shine?' is the definition.
The answer and definition can be both to do with fundamental existence as well as being verbs in their base form.
Maybe there's a link between them I don't understand?

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

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I've seen this clue in the Sydney Morning Herald.

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