Warning to support predecessor? (8)
I believe the answer is:
forebear
'predecessor?' is the definition.
(I've seen this before)
'warning to support' is the wordplay.
'warning' becomes 'fore' (I've seen this in other clues).
'to support' becomes 'bear' (I've seen this before**).
'fore'+'bear'='FOREBEAR'
(Other definitions for forebear that I've seen before include "Older relative" , "Ancestor" , "One of an earlier generation" , "one from the past" , "predecessor?" .)