Picnic to be suspended after unpleasant matter (8)

I believe the answer is:

pushover

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'picnic' is the definition.
(I know that picnic can be written as pushover)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for pushover that I've seen before include "One is easily defeated or outwitted" , "One's easily convinced" , "Something easily done" , "Topple - easy opponent" , "breeze" .)

I've seen this clue in The Times and The Sunday Times.

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