Support each terrible pain (8)
I believe the answer is:
backache
'pain' is the definition.
(I know that backache is a type of ache)
'support each terrible' is the wordplay.
'support' becomes 'back' (to back is to support or endorse).
'terrible' indicates an anagram.
'each' with letters rearranged gives 'ache'.
'back'+'ache'='BACKACHE'
(Other definitions for backache that I've seen before include "Eg, lumbago" , "common complaint" , "Eg, lumbar pain" , "Spinal pain" , "Pain in rear of body" .)