Clotet, 40, was dismissed earlier this month after losing 2-1 to relegation candidates Bury, with the former Leeds United assistant manager leaving the U's in 12th place and nine points behind the top six.
Numerous names have been linked with the job, with former Chelsea midfielder Frank Lampard the favourite to take over at the Kassam Stadium despite lacking in any kind of managerial experience.
However, Everton's second string boss Unsworth is now second favourite at 5/2 with SkyBet to take over at United after a decent job in charge of the Toffees senior side earlier this season.
Unsworth, 44, reassumed his position as boss of the Everton Under-23's after eight games in charge during in which the Toffees board looked to replace Ronald Koeman's successor - eventually choosing Sam Allardyce.
He only managed two wins, but he did stem the flow of goals and made his side harder to beat, ending his short spell in charge with an emphatic 4-0 win over struggling West Ham United at Goodison Park.
It remains to be seen if Oxford will look to tempt Unsworth with a stint in charge of the League One outfit, or instead look to land Chelsea legend Lampard.