What does the cryptic crossword clue "Jack counts up – he quickly passes 5 (8)" mean?

The wordplay uses a reversal. AB (synonym="sailor, jack") + RELIES (reversal="counts [on]") = ABSEILER The answer is ABSEILER.

Jack counts up – he quickly passes 5 (8)

Guardian Cryptic #29584 | 2 Down | 2025-01-06 flower