Hapless pope, in poorly-designed trousers, looks ridiculous (12)

I believe the answer is:

preposterous

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'ridiculous' is the definition.
(I know that ridiculous can be written as preposterous)

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

(Other definitions for preposterous that I've seen before include "Utterly absurd" , "Crazy" , "Laughable" , "Quite absurd" , "Ludicrous" .)

I've seen this clue in The Irish Times.

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