Stomach change of name and d.o.b. (7)
I believe the answer is:
abdomen
'stomach' is the definition.
(synonyms)
'change of name and d o b' is the wordplay.
'change of' indicates anagramming the letters.
'and' says to put letters next to each other.
'name'+'d'+'o'+'b'='namedob'
'namedob' with letters rearranged gives 'ABDOMEN'.
(Other definitions for abdomen that I've seen before include "Site of corporation" , "4 part of insect" , "Part of body containing the stomach" , "Belly" , "corporation's site" .)