Infant Ruth? (4)
I believe the answer is:
babe
This clue is a double definition.
'infant' is the first definition.
(synonyms)
'ruth?' is the second definition.
(synonyms)
(Other definitions for babe that I've seen before include "Very young child (often found in arms)" , "child still very young" , "Tiny child" , "Ruth, for example" , "good-looking young lady" .)