Clue: Exiled sailor found going round islands (10)
Answer: OSTRACISED
Explanation: Definition: Exiled
An envelope ('going round') of I ('island') in OS (Ordinary Seaman, 'sailor') plus TRACED ('found'). The answer has an interesting history: in Athens of the fifth century BC, one person a year could be exiled for ten years, by a majority vote; the votes consisted of the person's name written on a potsherd, a piece of broken pottery (ostrakon). Marine biologists and assiduous crossword solvers might also come across ostracods, tiny members of the Crustacea with a bivalve-like shell.