Where soldiers may be caught leaving special units (4)
I believe the answer is:
amps
'units' is the definition.
(the amp is a unit of electrical current)
'where soldiers may be caught leaving special' is the wordplay.
'where soldiers may be' becomes 'camp'.
'caught' becomes 'c' (cricket abbreviation).
'leaving' indicates named letters should be taken away.
'special' becomes 's' (common abbreviation as in Special Air Service).
'camp' with 'c' taken away is 'amp'.
'amp'+'s'='AMPS'
(Other definitions for amps that I've seen before include "Current measures" , "'Units of electric current, in short (4)'" , "concert gear" , "Basic units of electric current" , "Spam (anag)" .)