What does the cryptic crossword clue "Article missing its last odd loose thread (5)" mean?

The definition is "loose thread". The wordplay uses a charade (building blocks). TH (synonym="TH") + RUM (synonym="RUM") = THRUM The answer is THRUM.

Article missing its last odd loose thread (5)

Times Cryptic #29038 | 21 Down | 2024-10-03 flower