Was concerned about cutting scoundrel (5)
I believe the answer is:
cared
'was concerned' is the definition.
(had a care)
'about cutting scoundrel' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'cutting' is an insertion indicator (some letters cut their way into a word).
'scoundrel' becomes 'cad' (cad is a kind of scoundrel).
're' inserted inside 'cad' is 'CARED'.
(Other definitions for cared that I've seen before include "Felt affection (for)" , "Felt concern or interest" , "Was concerned" , "Tended" , "had feelings" .)