The Omagh man is due to have a scan to assess the damage to his left knee, but early indications are that he is facing a lengthy absence.
He fell awkwardly in the tenth minute of his club’s senior championship clash with Coalisland at Carrickmore.
Moments earlier, Clarke had scored a brilliant goal, which turned out to be decisive in his side’s 1-15 to 1-13 win.
The versatile Clarke has been a key figure for the Red Hands this season, playing at full back, wing back, and at midfield in their preliminary round win over Down last weekend.
However, he is likely to miss out on two fronts as club and county target championship success in the weeks ahead.