Son, worried and frightened (6)
I believe the answer is:
scared
'frightened' is the definition.
(synonyms)
'son worried' is the wordplay.
'son' becomes 's'.
'worried' becomes 'cared'.
's'+'cared'='SCARED'
'and' acts as a link.
(Other definitions for scared that I've seen before include "Thing which precipitates an event" , "having kittens" , "Frightened or intimidated" , "Fearful, anxious" , "Afraid, anxious" .)