Short-lived rains developed - shelter outside (9)
I believe the answer is:
transient
'short-lived' is the definition.
(synonyms)
'rains developed shelter outside' is the wordplay.
'developed' indicates an anagram.
'shelter' becomes 'tent' (canvas shelter).
'outside' means one lot of letters goes inside another (some letters go outside others).
'rains' anagrammed gives 'ransi'.
'ransi' inserted inside 'tent' is 'TRANSIENT'.
(Other definitions for transient that I've seen before include "Lasting a short time" , "gone in a trice!" , "Temporary worker" , "on the move" , "Lasting little time" .)