Of the body (8)
(Other definitions for corporal that I've seen before include "Of the body, say punishment" , "Like old-fashioned punishment" , "material" , "soldier?" , "Bodily" .)
'of the body' is the definition.
(I've seen this in another clue)
This is all the clue.
(Another definition for somatic that I've seen is " Of the body".)