Use of "do we" in the sentence "Only after 10pm do we actually sort out the mess."

Consider the use of the words "do we" in this sentence:

Only after 10pm do we actually sort out the mess.

Can someone give me the technical name for this usage of "do we"? Is it called something? Is there a webpage which explains when this is used?

Thanks

"Do we" is called subject-auxiliary inversion. This occurs in declarative clauses only when certain types of element are put in front position. Negatives are one very obvious type of element that trigger subject-auxiliary inversion when fronted:

"Never had I seen such chaos". "At no stage were they in danger".

"Only" is not negative, but it is semantically close to a negative, in that "Only John liked it", for example, entails 'No one other than John liked it'. The inversion is also found with some items that are not similar to negatives:

"John enjoyed it and so did Robert".