Saracens’ Billy Vunipola found not guilty of head-butting Mathew Tait

• Vunipola clear to play against Clermont Auvergne on Saturday• Mark McCall: Billy’s eyes were firmly on the ball the whole timeBilly Vunipola will be available for Saracens’s European semi-final against Clermont Auvergne after being found not guilty of head-butting Leicester’s Mathew Tait last weekend. A Rugby Football Union disciplinary panel ruled the collision was unintentional and has cleared the England No8 to play in Saturday’s game.Saracens strongly believed Vunipola should not have been cited in the first place, insisting the 22-year-old did nothing wrong. Video footage made available…