Sweet affectionate soldier (7)
I believe the answer is:
fondant
'sweet' is the definition.
(fondant is a kind of sweet)
'affectionate soldier' is the wordplay.
'affectionate' becomes 'fond' (synonyms).
'soldier' becomes 'ant' (soldier ant is a type of ant).
'fond'+'ant'='FONDANT'
(Other definitions for fondant that I've seen before include "Thick creamy sugar paste" , "Soft sweet" , "Sugary paste for sweets" , "Thick sugar paste used for icing cakes" , "Sweet paste of sugar, water, and flavouring" .)