With the international break looming, United top the table on 32 points, one ahead of champions Chelsea who have a game in hand.
Toone's sending-off for an altercation with Spurs midfielder Eveliina Summanen (24) in the 80th minute will see her miss three games, including a cup game against Durham and WSL games against bottom side Leicester City at home and Chelsea away.
After a first half lacking in decent goal-scoring chances, Manchester United upped the tempo in the second and began forcing saves from Tinja-Riika Korpela (36) in the Spurs goal, with Toone also hitting the far post with a cross-shot.
Leah Galton (28) finally broke the deadlock in the 67th minute, out-muscling a defender to win a ball from the right into the box and rifling home from close range.
Bethany England (28) wasted little time bringing Spurs level, latching on to a quick free kick and tearing towards the United goal before curling a brilliant shot past Mary Earps (29).
But her joy at scoring a fourth goal in five games proved to be short-lived.
The ball was in the Spurs net again just 14 seconds after the restart, Molly Bartrip (26) netting an own goal as she tried to deal with another ball into the box from the right, this time from Lucia Garcia (24).
The visitors looked set to coast to victory until Toone's red card threw Spurs a lifeline. But despite a late surge, the home side were unable to fashion an equaliser as United held on to win.
On Saturday, Manchester City beat Arsenal 2-1 to climb above them in the table into third spot, three points behind Manchester United and two behind Chelsea.
In Sunday's other games, Brighton host Aston Villa while Leicester travel to Liverpool.
