Part of the garrison - a regiment tracking subs (5)
I believe the answer is:
sonar
'part of the garrison a regiment tracking subs' is the definition.
I can't judge whether this defines the answer.
'part of the garrison a regiment tracking' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'SONAR' can be found hidden inside 'garrison a regiment tracking'.
Can you help me to learn more?
(Other definitions for sonar that I've seen before include "Locating device" , "Echo sounder - arson (anag)" , "Underwater detection system" , "echo device" , "Underwater echo sounder" .)