Instrument carried by fliers on a raid (5)
I believe the answer is:
sonar
'instrument' is the definition.
(eg instrument on a plane)
'carried by fliers on a raid' is the wordplay.
'carried by' indicates a hidden word.
'SONAR' can be found hidden inside 'fliers on a raid'.
(Other definitions for sonar that I've seen before include "echo device" , "Underwater detection system" , "Echo-sounding equipment" , "Underwater echo sounder" , "location device" .)