Terrified by concern in case of scaffold (6)
I believe the answer is:
scared
'terrified' is the definition.
(thesaurus)
'concern in case of scaffold' is the wordplay.
'concern' becomes 'care' ('care' can be a synonym of 'concern').
'in' means one lot of letters goes inside another.
'case of' says to hollow out the word (remove centre letters) (outsides of).
'scaffold' with its centre taken out is 'sd'.
'care' put within 'sd' is 'SCARED'.
'by' acts as a link.
(Other definitions for scared that I've seen before include "Frightened or intimidated" , "Frightened or apprehensive" , "Nervous" , "Afraid, anxious" , "Afraid of cedars" .)