sackable

adj

1. Sufficiently severe to warrant the perpetrator being sacked.

   “This follows the confirmation that Gilruth personally ordered the cancellation of engineering works in Fife last year, which is thought to have been the final straw for Gibb […]. Because her Fife constituency was materially affected by the cancellation, Scottish Conservative leader Douglas Ross, who raised Gibb's departure at First Minister's Questions on May 18, described the incident as a "clear-cut sackable offence".”