What does the cryptic crossword clue "A built-in bed needs repairing, beyond doubt (11)" mean?

The wordplay uses an anagram. anagram of A + BUILT-IN + BED = INDUBITABLE The answer is INDUBITABLE.

A built-in bed needs repairing, beyond doubt (11)

Daily Mail Cryptic #16575 | 1 Across | 2021-05-13 flower