Hurry in rain, perhaps (13)
I believe the answer is:
precipitation
This clue is a double definition.
'hurry' is the first definition.
(thesaurus)
'rain perhaps' is the second definition.
(rain is a kind of precipitation)
'in' is the link.
(Other definitions for precipitation that I've seen before include "Snow, rain, etc - impetuosity" , "Rain, hail, snow etc" , "rain, perhaps" , "Rain, snow, sleet or hail" , "Undue rushing" .)