Fly, carrying new tracking apparatus (5)
I believe the answer is:
sonar
'tracking apparatus' is the definition.
(sonar is used to track or detect objects)
'fly carrying new' is the wordplay.
'fly' becomes 'soar' (soaring is a kind of flying).
'carrying' means one lot of letters goes inside another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'soar' placed around 'n' is 'SONAR'.
(Other definitions for sonar that I've seen before include "echo device" , "Means of detecting" , "Underwater detection system" , "Echo-sounding equipment" , "Underwater location equipment" .)