Oh what wonders a second clap would've done.
"We go on 2, or 3, or 4!" But nope, 1...every time. Kudos to MSU for taking advantage of that.
Just for everyone's knowledge, generally speaking, the "clap" is a silent count.
A lot like any other form of "silent count" there is most likely only one movement. Leg left, arm extended downward, etc., to notify the center that the QB is ready for the ball. Every now and then they'll change it up to two "claps", "leg lifts" or whatever.
The "count" isn't actually the motion the QB makes for the snap. The count is actually the amount of "head nods" the Center makes. For example, they could determine that they will go on 2. What that means is that the the ball is snapped after 2 "head nods". Count on 3, then it's 3 head nods.
There are many advantages to the "clap". This allows for the Center to be able to look downfield and read the D. The other silent counts require Center to watch the QB during all pre-snap stuff.
Chip Kelly's Eagles used one where Center was still able to look downfield by having the guard watch the QB pre-snap. Then taps the Center when QB is ready.
Disadvantage for all silent counts. Everyone on OL stares at the Center for those nods.