Cradlesong (7)
I believe the answer is:
lullaby
'cradlesong' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for lullaby that I've seen before include "Soothing song for baby - Brahms wrote a good one" , "Soothing song for infants" , "Gentle song to put baby to sleep" , "Berceuse" , "soothe" .)