Means of locating a girl in a car (5)
I believe the answer is:
radar
'means of locating' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'a girl in a car' is the wordplay.
'a girl' becomes 'ada'.
'in' indicates putting letters inside.
'a car' becomes 'rr' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ada' placed within 'rr' is 'RADAR'.
Can you help me to learn more?
(Other definitions for radar that I've seen before include "Remote detection system" , "Remote detection device" , "Range-finding and detection system" , "Instrument to detect and locate distant objects" , "Pulse detection system" .)