Oswald's unlucky formulation (4,3)
I believe the answer is:
sods law
'unlucky formulation' is the definition.
I don't understand the rest of the clue.
(Other definitions for sods law that I've seen before include "This is bound to happen" , "Expect the worst!" , "this means I'm bound to get some!" , "Why one can't win" , "Pessimistic theory" .)