What does the cryptic crossword clue "Go in sea haphazardly and fret? (7)" mean?

The definition is "fret?". The wordplay uses an anagram. anagram of GO + IN + SEA = AGONISE; definition: "fret?" The answer is AGONISE.

Go in sea haphazardly and fret? (7)

Daily Mail Cryptic #17283 | 21 Down | 2024-01-31 flower