Three in rugby play to glean scraps (7,4)

I believe the answer is:

penalty goal

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'three' is the definition.
Both the definition and answer are adjectives.
Maybe they are linked in a way I don't understand?

'rugby play to glean scraps' is the wordplay.
'play to glean' anagrams to 'PENALTY GOAL'.
Though, I am unsure how the anagram is indicated.

'in' acts as a link.

Can you help me to learn more?

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

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