Even so, the jeers that reverberated around St. James' Park at the final whistle emphasised to manager Graeme Souness that the natives remain restless.
After taking the lead with a stunning Nolberto Solano free-kick, Newcastle then looked doomed to defeat after another Titus Bramble howler gift-wrapped Boro a second-half equaliser, before substitute Jimmy Floyd Hasselbaink drove them in front with just three minutes remaining.
But Geordie-boy Clark came to the rescue with a crucial volley - his first goal since rejoining the club.
The match was disappointing as both sides showed why they are in the wrong half of the table.
If anything, Boro played the more fluent football and in Yakubu, Mark Viduka and Hasselbaink had the players most capable of scoring.
At the other end, Albert Luque had his best game for Newcastle and came close to his first goal, only to be denied by the woodwork, while Alan Shearer battled as valiantly as ever.
Newcastle almost went ahead after five minutes when Solano's quick reactions released Luque from a free-kick. The Spain international went on to round Boro goalkeeper Mark Schwarzer only to see his shot strike the foot of the post.
Viduka then missed the easiest chance he is ever likely to get, after 25 minutes. James Morrison and Stuart Parnaby linked well for the latter to cross, but Viduka somehow fired the ball over the bar from just four yards.
United went straight up the other end and scored the opening goal. It came from another free-kick after Shola Ameobi had been fouled. Solano took responsibility some 25 yards from goal and curled a delightful shot beyond the Aussie keeper.
On the left side, Robbie Elliott and Ameobi had a nightmare against Morrison and the surging Parnaby and it was no surprise when they made way at the break for Celestine Babayaro and Charles N'Zogbia.
The turning point came nine minutes after the break when Bramble surged forward but misplaced a pass and United were torn apart. Morrison drove forward and whipped over a perfect pass for Yakubu to bundle in the equaliser.
It looked like remaining that way until three minutes from time when Parnaby put Hasselbaink in the clear and the Dutchman added a perfect finish.
United had one final throw of the dice with a late corner and made it count. Solano's cross was never really cleared and when it dropped, Clark volleyed through the crowded penalty area to start mass celebrations.