Passing rains ripped into canvas shelter (9)
I believe the answer is:
transient
'passing' is the definition.
('transient' can be a synonym of 'passing')
'rains ripped into canvas shelter' is the wordplay.
'ripped' indicates an anagram.
'into' means one lot of letters goes inside another.
'canvas shelter' becomes 'tent' (I've seen this before).
'rains' anagrammed gives 'ransi'.
'ransi' put within 'tent' is 'TRANSIENT'.
(Other definitions for transient that I've seen before include "gone in a trice!" , "Fleeting" , "fugitive" , "Lasting a short time" , "on the move" .)