On-loan Colchester City attacker Denny Johnstone, pictured inset, took just 80 seconds to fire the Perth men in front but Alex Schalk’s penalty reply early in the second half set up a frantic and breathless second half.
County’s poor first half made way for a vastly improved second-half performance, but Clark stole the show with a double reflex save from Billy Mckay to cap a brilliant performance.
The Dingwall team at least rose off bottom place on goal difference, while Saints may view this as a missed opportunity to rise into the top six.
The visitors took the lead within 80 seconds – and with startling ease. David Wotherspoon delivered a fine ball from the left to Johnstone, who seemed to have far too much time and space to bundle a finish past keeper Scott Fox from close range.
Saints were assured in their gameplan, absorbing County’s early attacking endeavours in the swirling snow.
The hosts certainly tried to ask questions and were at their best in glimpses when Alex Schalk and Eagles took the ball to feet.
Saints were composed on the counter-attack, without finding much joy in behind the Dingwall defence.
Liam Craig’s powerful strike was saved at the second attempt by Fox but the Perth men would have been more than satisfied by the 1-0 lead they held at half-time.
The offside flag frustrated Saints early in the second half after Michael O’Halloran’s drive hit the net, with County defensively shaky.
But the hosts were back in business after a flurry of pressure earned a penalty. Craig Curran rolled a pass towards the centre of the 18-yard line where Chris Eagles was clearly chopped down by Saints’ Chris Millar just inside the area.
Schalk stepped up for the penalty and calmly sent Clark the wrong way for the equaliser. Saints threatened to restore the away lead but Johnstone saw a strike saved before, on the rebound, Chris Routis made a desperate block as Wotherspoon went for the finish.
An incredible sequence, peppering St Johnstone’s goal, saw Clark brilliantly deny the Dingwall side after 75 minutes. Jason Naismith’s low drive was blocked, Schalk struck the post on the rebound, and Mckay saw two follow-up attempts thwarted by the Perth goalkeeper.
It was end-to-end stuff, right to the death, with both sides working tirelessly into three minutes’ stoppage time until the final whistle sounded.
ROSS COUNTY: Fox, Fraser, Naismith, Davies (Lindsay 45), van der Weg, Eagles (Keillor-Dunn 60), Routis, Chow, Gardyne, Schalke, Curran (Mckay 72). Subs not used: Dow, Mikkelsen, O’Brien, McCarey .
ST JOHNSTONE: Clark, Tanser, Shaughnessy, Anderson, Millar, S MacLean, Wotherspoon (Alston 83), O’Halloran, Johnstone (Cummins 71), Foster, Craig. Subs not used: Mannus, K McClean, Scougall, Gordon, Easton.
Referee: G Aitken. Attendance: 3,636.