Here's my problem with that 8 letter thematic.
In all other examples, apart from the the thematic relationship, there is absolutely nothing else connecting them - wordplay but no definition
In this instance, however, one Chambers definition of the answer is "easily affected or altered" which is basically "easily upset" (if you alter a crime scene, for example, you could be said to have upset it), meaning the clue has the routine wordplay and definition components - unlike the other eleven.
All this, of course, assumes we're talking about the same clue:-)