Boisterous sit-in calls for scraps (10)

I believe the answer is:

scintillas

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'scraps' is the definition.
Although both the answer and definition are plural nouns, I don't understand how one could define the other.

'boisterous sit-in calls' is the wordplay.
'boisterous' indicates anagramming the letters (I've seen this in other clues).
'sit'+'in'+'calls'='sitincalls'
'sitincalls' is an anagram of 'SCINTILLAS'.

'for' acts as a link.

Can you help me to learn more?

I've seen this clue in The Everyman puzzle in The Observer.

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