A Northern Territory six-footer (3)

I believe the answer is:

ant

'six-footer' is the definition.
(ants have six feet)

'a northern territory' is the wordplay.
'northern territory' becomes 'nt' ().
'a'+'nt'='ANT'

(Other definitions for ant that I've seen before include "Social worker" , "Six-footer" , "Proverbially hard-working insect" , "Hill-dweller" , "Colonial insect?" .)

I've seen this clue in the Sydney Morning Herald.

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