Colonial soldier? (4,3)

I believe the answer is:

army ant

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'colonial soldier?' is the definition.
(I've seen this in another clue)

'colonial soldier?' is the wordplay.
'colonial' becomes 'army' (I can't justify this - if you can you should believe this answer much more).
'soldier?' becomes 'ant' (soldier is a type of ant).
'army'+'ant'='ARMY ANT'

Can you help me to learn more?

(Other definitions for army ant that I've seen before include "Foraging insect" , "Soldier, perhaps" , "Stinging insect" , "Group-foraging insect" , "tropical insect" .)

I've seen this clue in The Sun and the USA Today.

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