Santorelli also netted the equalizer late in regulation time, jamming in a rebound on a power play with 3 minutes remaining to make it 2-2.
Clemmensen finished with 34 saves and David Booth also scored for Florida, which won for only the second time in six games.
Marc-Andre Bergeron and Sean Bergenheim tallied for the Southeast Division-leading Lightning.
Ellis stopped 24-of-26 shots for Tampa Bay.
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