Said to contribute to a major alert (4)
I believe the answer is:
oral
'said' is the definition.
(both can mean spoken)
'contribute to a major alert' is the wordplay.
'contribute to' says the answer is hidden in the clue (I've seen 'contributing to' mean this (the answer contributes to part of the clue )).
'ORAL' is hidden in the letters of 'major alert'.
'to' is the link.
(Other definitions for oral that I've seen before include "Type of exam" , "Kind of examination" , "See 18" , "Type of examination" , "from the trap" .)