Despite being fouled for the penalty, Benteke has now failed to score in all 11 of his league appearances at Selhurst Park this season.
The Belgium striker did, though, provide a constant threat against the Magpies and was only denied breaking that home drought by Clark's 89th-minute block.
Benteke also linked up well with his teammates, and with new signing Alexander Sorloth an unused substitute, the striker clearly remains a key element in Palace's survival bid having scored in the midweek draw with West Ham.
Newcastle had to dig deep to avoid what would have been just a second defeat in six games, with the visitors indebted to goalkeeper Darlow and defender Clark.
Clark was at fault for the penalty with a clear tug on Benteke spotted by the assistant referee, but equally his block from the Belgium striker ultimately secured what could be a crucial point at the end of the season.
Newcastle's opener was slightly against the run of play as Ayoze Perez applied a crucial touch to help Kenedy's corner on for Diame to sweep home.
Diame's finish was Newcastle's first goal in the opening 45 minutes since the now departed Henri Saivet found the net at West Ham on 23 December.
Newcastle could have gone 2-0 up just before half-time as Palace goalkeeper Wayne Hennessey blocked from the lively Kenedy on his second appearance for the club, before making a flying save to turn away Perez's effort not long after.
Newcastle did not have a touch of the ball inside the Crystal Palace penalty area in the entire second half
But from that point in the 32nd minute until a late flourish, Newcastle did not register a shot at the Palace goal.
New signing Islam Slimani was not selected due to an ongoing thigh injury, while striker Dwight Gayle has now not scored in his last 14 league appearances.