What does the cryptic crossword clue "Crane unit needs fixing? Not sure (9)" mean?

The definition is "Not sure". The wordplay uses an anagram. anagram of CRANE + UNIT = UNCERTAIN; definition: "Not sure" The answer is UNCERTAIN.

Crane unit needs fixing? Not sure (9)

Daily Mail Cryptic #16654 | 7 Down | 2021-09-01 flower