The Devils’ biggest free agent signing former Ranger forward Ryane Clowe left Thursday’s preseason game against the Islanders early in the first period with what coach Pete DeBoer described as “a charley-horse type injury.” He played just 2:01 on three shifts. “I don’t believe it’s serious” DeBoer said after the Devils fell 5-3. Clowe 30 signed a five-year $24.25 million contract this offseason.