Godparent quietly breaks child's soldiers (7)
I believe the answer is:
sponsor
'godparent' is the definition.
(I've seen this in another clue)
'quietly breaks child's soldiers' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet).
'breaks' means one lot of letters goes inside another (inserted letters break into the word).
'child's' becomes 'son's' (male child).
'soldiers' becomes 'OR' (Other Ranks).
'p' put inside 'sons' is 'spons'.
'spons'+'or'='SPONSOR'
(Other definitions for sponsor that I've seen before include "Provide finance for" , "One who backs" , "Promoter, godparent" , "Provide backing" , "Godparent at a baptism" .)