Army on exercises get record (4)
I believe the answer is:
tape
'record' is the definition.
('tape' can be a synonym of 'record')
'army on exercises' is the wordplay.
'army' becomes 'ta' (abbreviation for Territorial Army).
'on' is a charade indicator (letters next to each other).
'exercises' becomes 'pe'.
'ta'+'pe'='TAPE'
'get' acts as a link.
(Other definitions for tape that I've seen before include "Fabric strip; record" , "Band" , "Type of record" , "Record; cassette" , "Sticky strip" .)