What does the cryptic crossword clue "Chap finding voyaging at sea hard work (5,5)" mean?

The wordplay uses a charade (building blocks). anagram of HE (synonym="HE") + VOYAGING (synonym="VOYAGING") = HEAVYGOING The answer is HEAVYGOING.

Chap finding voyaging at sea hard work (5,5)

Guardian Cryptic #29210 | 18 Across | 2023-10-25 flower