Brolly (8)
I believe the answer is:
umbrella
'brolly' is the definition.
(I know that umbrella is a type of brolly)
This is all the clue.
(Other definitions for umbrella that I've seen before include "Blanket" , "What goes up when rain comes down?" , "Brolly" , "What may go up when the rain comes down" , "For protection against the elements" .)