Stefan Scougall struck the only goal of the game after 23 minutes to keep the Blades in the top half of League One having not long ago been stuck in the relegation zone.
While the FA Cup quarter-finalists are on a role, this result was a further blow to the Dons' fading play-off hopes.
Clough said: "We said after the Gillingham game that that was our best three points of the season, but that's been superseded here.
"It's because of the circumstances of it - the quality of opposition, what's gone into our games of late.
"To put what we did in here was quite staggering really.
"The thing we could have done differently was that we could have got a second goal at the start of the second half.
"It's happened a few times when we've gone in at half-time one-nil up and the home team then put us under pressure and turn the tables.
"For 20 minutes in the second half we could have had that second goal because we played well enough to get one.
"That was above and beyond - the hard work they put in was on a different level and to keep a clean sheet again along with another away victory is incredible."
- Sports & Recreation