Hiya Pastille,
Just read your post and thought I should comment on it as I used the same anagram for my clue.
In your clue using 'see disruption as fortuitous'.
If only the letters of 'disruption' are the anagram fodder, then yes, it would have been fair, however, because it's 'see disruption' it leaves the letters 'SEE' unaccounted for. This is the reason I put 'Doctors' for the anagrind in my clue because it wouldn't quite look right and fair to leave the solver guessing.
Usually when using words that make anagrinds themselves from part of the final answer and thus qualify to leave out thus anagrinds, they become &lit clues.
Here is an example:
Hips that can be found on the seabed? (9)
Answer: Shipwreck
Hips is the anagram of 'Ship' and the anagrind is 'wreck' which is part of the final answer, so can be omitted and qualify for an &lit because of its self explanatory solution.
This clue still has the Def 'can be found on the seabed' so really it's a partial &lit, but I did post something this week about &lit clues but forgot which thread it was on.
Hope that kinda made sense, anyone else is free to comment.