Sign to precede terrible rain? I may help you find the literature (9)
I believe the answer is:
librarian
'i may help you find the literature' is the definition.
'sign to precede terrible rain?' is the wordplay.
'sign' becomes 'libra' (sign of the zodiac**).
'to precede' means one lot of letters go next to another.
'terrible' indicates an anagram.
'rain' with letters rearranged gives 'rian'.
'libra'+'rian'='LIBRARIAN'
(Other definitions for librarian that I've seen before include "job!" , "Custodian of a collection of books" , "Person in charge of books etc" , "Bookish type" , "Bookkeeper" .)