The most common and most likely answer to this crossword clue is the 7 letter word CHARADE
I've seen this crossword clue in Financial Times
C
H
A
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A
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More clues leading to the result CHARADE
- Daily forced to cancel leader in ridiculous pretence
- Tea awfully dear — it's a travesty
- Had race fixed as a ridiculous pretence
- Notice in Daily Express initially a mockery?
- Corrupt archdeacon sacrificing Tory in absurd pretence
- Deception, fishy fizzy drink?
- Arguably dirtier exhibitionist starts after cleaner act
- Cary Grant film poster within reach perhaps
- Daily forced to ditch front cover in farcical event
- Care had to be exercised in this absurd pretence
Buddy explains!

The straight part
We know that "that’s absurd" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that’s absurd = charade.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CHARADE mean?
CHARADE noun- A genre of riddles where the clues to the answer are descriptions or puns on its syllables, with a final clue to the whole.
- A single round of the game charades, an acted form of the earlier riddles.
- A play resembling the game charades, particularly due to poor acting.
- A deception or pretense, originally an absurdly obvious one but now in general use.
- To act out a charade (of); to gesture; to pretend.