Clayton got a second silver medal as Great Britain were second in the team competition, with Ireland third.
The senior men's race was the final event on the schedule with a 12:30 start time.
Uganda swept the top four places and earned a gold team medal with a perfect score of 10.
Philip Kiplimo won over the three-lap 13.56km course in 54:22 putting more than half-a-minute between himself and his nearest rival Geoffrey Kusuro, with his better-known compatriot crossing the line in 55:06.
Team mates Nathan Ayeko and Peter Kibet were third and fourth respectively in 55:19 and 55:27 respectively.
The first non-Ugandan home was Italy's Bernard Dematteis in fifth place and the lead home the Italian team to the silver medals with Turkey, led by six-time European champion Arslan Ahmet in eighth place, taking the bronze medals.
David Okeyo, like Chairman of the IAAF Cross Country Commission and Otto Klappert, like Honorary Chairman of the same Commission, Zbigniew Polakowski, PZLA VicePresident and all WMRA Council members attended to the competition.
At the closing ceremony the WMRA flag passed by LOC of Krynica Zdroj trought the WMRA President Bruno Gozzelino to mr. Sergio Baldo, FIDAL Council member and Chief Delegation of Italian team, like representant of the LOC of the next 30. WMRA World Mountain Running Championships 2014 in Italy, at Casette di Massa (Toscana Region).