Navel (9)
'navel' is the definition.
(synonyms)
This is all the clue.
(Other definitions for bellybutton that I've seen before include "Navel" , "Vestige of original attachment to one's mother" .)
'navel' is the definition.
(I know that navel can be written as umbilicus)
This is the entire clue.
(Other definitions for umbilicus that I've seen before include "Navel" , "Something in the tummy" .)