18/26 across
1
main
partner
(7)
1 main partner (7)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
The 1 is a cross-reference to another clue providing the definition of this fish. The wordplay is a charade: SEA (main, the ocean) + WIFE (partner) = SEAWIFE.