Mere nit-picking, it gets Calvin no end upset! (5)

I believe the answer is:

cavil

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'mere nit-picking it' is the definition.
I can't tell whether this defines the answer.

'calvin no end upset' is the wordplay.
'no end' means to remove the last letter.
'upset' is an anagram indicator.
'calvin' with its last letter taken off is 'calvi'.
'calvi' anagrammed gives 'CAVIL'.

'gets' is the link.

Can you help me to learn more?

(Other definitions for cavil that I've seen before include "Complain" , "Minor complaint" , "Raise petty objections" , "Make trivial objection" , "Carp" .)

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