Child's beginning to get tender chest (6)
I believe the answer is:
coffer
'chest' is the definition.
(I know that coffer is a type of chest)
'child's beginning to get tender' is the wordplay.
'child's beginning' becomes 'c' (I am not sure about this - if you are sure you should believe this answer much more).
'to get' is a charade indicator (letters next to each other).
'tender' becomes 'offer' (synonyms).
'c'+'offer'='COFFER'
Can you help me to learn more?
(Other definitions for coffer that I've seen before include "Strongbox" , "A large strong box for valuables" , "Treasury - chest for valuables" , "Treasure chest" , "Small chest for keeping valuables" .)