Son was concerned, getting frightened (6)
I believe the answer is:
scared
'frightened' is the definition.
(scared means frightened or fearful)
'son was concerned getting' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'was concerned' becomes 'cared' (had a care).
'getting' says to put letters next to each other.
's'+'cared'='SCARED'
(Other definitions for scared that I've seen before include "Afraid, anxious" , "Frightened or apprehensive" , "Frightened, alarmed" , "Frightened or intimidated" , "Afraid of cedars" .)