Feeling concern about knave stealing vehicles (10)
I believe the answer is:
carjacking
'feeling concern about knave stealing vehicles' is the definition.
I can't tell whether this definition defines the answer.
'feeling concern about knave' is the wordplay.
'feeling concern' becomes 'caring' ('care' can be a synonym of 'feel concern').
'about' means one lot of letters goes inside another.
'knave' becomes 'jack' (synonyms).
'caring' going around 'jack' is 'CARJACKING'.
Can you help me to learn more?
(Other definitions for carjacking that I've seen before include "Maybe taking taxi from driver" , "Vehicle stealing" , "crime?" .)