David Moyes says he would never have allowed the clause to be inserted in Jermain Defoe's contract which will see the striker quit Sunderland on a free transfer this summer.
The 34-year-old will leave for nothing after the club's relegation from the Premier League - as revealed by Sportsmail in March - with Bournemouth, West Ham and West Brom chief among his suitors.
But Black Cats boss Moyes is surprised that Defoe's deal - which was extended to 2019 last June - contains the escape clause.
'In my time as manager I wouldn't have allowed a clause to be in there but it is and we have to honour the contract,' said Moyes, who replaced Sam Allardyce in July.