It came in the Grizzlies' third game in less than 48 hours against Colorado, which never trailed until Estoclet's power-play goal with 1:26 left in overtime.
"It feels great," said coach Kevin Colley. "I didn't think we were fantastic tonight, but we found a way to win."
Colorado dominated the third period and took a 2-1 lead on Trent Daavettila's goal with 12:26 remaining.
Enter Estoclet. With 4:23 left, Colin Vock dug the puck out of a crowd and passed to Estoclet, who charged the net. When Colorado goalie Kyle Jones committed to him, Estoclet slid a pass to Clendenning, who tied the game.
"Just a good play on the wall by Vock ... and Clendenning was there on the back door for a nice little tap-in," Estoclet said.
In overtime, the Grizzlies got a break when Colorado's Kevin Ulanski was called for hooking Jimmy Martin with 1:40 to play.
Utah won the face-off and quickly worked the puck to Estoclet. Jones stopped his slap shot, but the Grizzlies controlled the rebound. They got it back to Estoclet in the same spot on the ice, and this time, he blasted home the game-winning goal.
"It's always nice to get a power play in overtime," Estoclet said. "I had a lot of time to shoot and was lucky enough to get it past him."
The Eagles were incensed with referee Andy Thackaberry for calling such a late penalty. Ulanski had to be restrained by a linesman when he came out of the penalty box after Estoclet's goal, and Colorado assistant coach Greg Pankewicz was given a postgame misconduct penalty.
Grizzlies 3, Eagles 2 (OT)
R Adam Estoclet scores the game-winning goal in OT
• The Grizz move within one point of clinching a playoff berth.