Alma came up with back-to-back stops in the third quarter for Clarksville's unconventional offense to go up 41-20 with 2:53 left in the quarter.
After an 0-3 start on the season, the Airedales (4-3, 4-0) won their next four, including Friday's homecoming game, 55-29.
Keegan Rosebeary finished with 10 carries for 124 yards and three touchdowns for the Airedales. Rosebeary scored the first touchdown and added two more in the second half on runs of 50 and 5 yards.
Landon Blair threw three touchdown passes for the Airedales.
Both teams traded shots in the first quarter.
Clarksville (2-5, 1-3) struck first, but had to settle for a 22-yard field goal to take the first lead.
Alma answered with a pair of scores to claim the lead for good.
Rosebeary had a four-yard run and the Airedales were up 7-3. After Alma recovered the ensuing onside kick, Blair connected with Ben Henley on a quick two-yard pass. Seven plays later and Alma's lead extended to 13-3 with 2:52 remaining in the first quarter.
Blair hit Grayson Bailey for a short pass after Clarksville scored. Bailey broke free of a couple of tackles and scrambled 63 yards and Alma was up 20-10.
The Airedales began the second half with a 62-yard touchdown by Tanner Shelton. Not to be outdone, Clarksville's Jamie White capped a seven-play drive with A 25-yard run.