Suggs finally leaving Madness for senseless remark (7)

I believe the answer is:

inanity

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'remark' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for inanity that I've seen before include "Silliness in a tiny way" , "Puerility" , "Mindlessness" , "Folly" , "Senselessness - frivolous utterance" .)

I've seen this clue in The Independent.

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