Adult beaten becomes embarrassed (7)
I believe the answer is:
abashed
'embarrassed' is the definition.
(synonyms)
'adult beaten' is the wordplay.
'adult' becomes 'a' (abbreviation).
'beaten' becomes 'bashed'.
'a'+'bashed'='ABASHED'
'becomes' is the link.
(Other definitions for abashed that I've seen before include "taken aback" , "Made ashamed" , "Embarrassed or disconcerted" , "Ill at ease" , "floored" .)