Army group using a Continental method of getting info (4)
I believe the answer is:
unit
'army group' is the definition.
(group of soldiers)
'a continental method of getting info' is the wordplay.
'a continental' becomes 'un' ('a' in French - France is on the continent).
'method of getting info' becomes 'IT' (information technology).
'un'+'it'='UNIT'
'using' is the link.
(Other definitions for unit that I've seen before include "Detachment of soldiers" , "Body of soldiers" , "Single complete domestic fixture" , "Single item, maybe part of a set" , "detachment maybe" .)