Picked up a tissue with sign of a cold coming (6)
I believe the answer is:
sneeze
'sign of a cold coming' is the definition.
(a cold might make someone sneeze)
I cannot understand how the remainder of the clue works.
(Other definitions for sneeze that I've seen before include "Expel air from nose" , "Nasal eruption as caused by cold or dust" , "Explosive nasal release" , "Minor bodily explosion" , "involuntary reaction" .)