Sound of a sneeze causes clumsy sociopath to drop PC (7)
I believe the answer is:
atishoo
'sound of a sneeze' is the definition.
(I've seen this before)
'clumsy sociopath to drop pc' is the wordplay.
'clumsy' indicates an anagram.
'to drop' suggests deleting specific letters.
'sociopath' with 'pc' taken away is 'soioath'.
'soioath' with letters rearranged gives 'ATISHOO'.
'causes' acts as a link.
(Other definitions for atishoo that I've seen before include "Word to be sneezed at" , "Sound made on expiration" , "Sound of a sneeze" , "Sudden eruption" , "report of involuntary escape from trap?" .)