It detects a lawyer in Rolls-Royce (5)
I believe the answer is:
radar
'it detects' is the definition.
The definition suggests a singular noun which matches the answer.
'a lawyer in rolls-royce' is the wordplay.
'lawyer' becomes 'da' (abbreviation for District Attorney).
'in' is an insertion indicator.
'rolls royce' becomes 'rr' (short for Rolls Royce).
'a'+'da'='ada'
'ada' inserted inside 'rr' is 'RADAR'.
Can you help me to learn more?
(Other definitions for radar that I've seen before include "Instrument to detect and track distant objects" , "M.A.S.H. character; electronic range detector" , "Pulse detection system" , "Early warning system" , "Pulsed location-finder" .)