What does the cryptic crossword clue "Embarrassed by junior officer seen waving on a British vessel (3,6)" mean?

The wordplay uses a charade (building blocks). RED (synonym="embarrassed") + ENSIGN (synonym="junior officer") = REDENSIGN The answer is REDENSIGN.

Embarrassed by junior officer seen waving on a British vessel (3,6)

Guardian Cryptic #29034 | 14 Down | 2023-04-03 flower