Could ingredients ever be rat bones? (9)
I believe the answer is:
vertebrae
'bones?' is the definition.
(vertebra is a kind of bone)
'could ingredients ever be rat' is the wordplay.
'could ingredients' indicates anagramming the letters (I've seen this in other clues).
'ever'+'be'+'rat'='everberat'
'everberat' is an anagram of 'VERTEBRAE'.
(Other definitions for vertebrae that I've seen before include "Bony segments of the spinal column" , "Bits of bone" , "Backbone segments" , "Bones of back" , "Bones of the spinal column" .)