Champ getting to grips with algebraic characters oddly omitted four lines (8)

I believe the answer is:

clerihew

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'lines' is the definition.
(I've seen this before)

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

(Other definitions for clerihew that I've seen before include "Satire of rhymed couplets about a famous person" , ""George the Third/ Ought never to have occurred. One can only wonder/ At so grotesque a blunder.", for example" , "Bentley's jingle" , "Two-lined comic verse" , "Short comic verse about famous person" .)

I've seen this clue in The Telegraph.

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