Second judge dropping off? That's a bit strange (4)

I believe the answer is:

iffy

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

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for iffy that I've seen before include "Full of uncertainty" , "Doubtful (colloq.)" , "Sixth (RU) Nation" , "not kosher" , "Informally dubious, not definite" .)

I've seen this clue in The Irish Times.

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