What does the cryptic crossword clue "A cash reserve for moving aboard (6)" mean?

The definition is "m". The wordplay uses a charade (building blocks). A (synonym="A") + FLOAT (synonym="cash reserve") = AFLOAT The answer is AFLOAT.

A cash reserve for moving aboard (6)

Guardian Cryptic #28911 | 22 Down | 2022-11-10 flower