Crossword Genius

Obstacle on marshland where ship departs (6)

Ross

I believe the answer is:

remora

I'm a little stuck... Click here to teach me more about this clue!

But I can't explain it at all! Could you help me understand?

(Other definitions for remora that I've seen before include "Arm roe against suckerfish" , "Slender sea fish" .)

Want a hint initially instead of a full solution? Install my app