A concept with a lot of comedic potential.
Here is a suggested revision for your consideration:
A class-action settlement typo awards every resident of a commuter-bedroom town one million dollars IF nobody leaves for thirty days. Now the mayor must outwit the losing corporation's attempts to lure at least one resident across the border. (38 words)
My rationale:
Break the logline into 2 sentences. (Shorter sentences for folks with shorter attention spans--which is just about everyone these days.)
"Losing corporation" instead of "corporate saboteurs" because it tags the antagonist with big stakes on the other side of the bet.
"Mayor" instead of "clerk" because the former has more credible authority to enforce a lockdown. Of course, the clerk can be a supporting character, the mayor's sidekick.
"Bedroom-commuter town" instead of "bankrupt" because I suggest it is a bigger, more urgent, more direct, more personal complication for town residents than bankruptcy which can drag out in the courts for months and which will impact residents indirectly and unevenly. IOW: give residents more immediate and urgent skin in the game, more personal and *ongoing* temptations to leave town.
As in the 1971 comedy "Cold Turkey" where a tobacco company offers $25 million to any American town that quits smoking for 30 days. Going cold turkey isn't easy and the temptation to relapse can be irresistible and *ongoing* for the duration of the challenge.
FWIW