As of blundering clumsy people (4)
I believe the answer is:
oafs
'clumsy people' is the definition.
(I've seen this in another clue)
'as of blundering' is the wordplay.
'blundering' indicates an anagram (I've seen 'blunder' mean this).
'as'+'of'='asof'
'asof' anagrammed gives 'OAFS'.
(Other definitions for oafs that I've seen before include "Dolts" , "donkeys" , "Idiots" , "Louts on sofa" , "Boors or buffoons" .)