Sound of patient with cold: what might wipe nose, did you say? (7)
I believe the answer is:
atishoo
'sound' is the definition.
(I have seen 'Sound of sneeze' mean 'atishoo' so perhaps 'sound' could also mean 'atishoo')
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for atishoo that I've seen before include "Sound made on expiration" , "hay-fever sufferer may interject this" , "Word to be sneezed at" , "Sudden eruption" , "Sneezing sound" .)