Interact, but be heartless and unharmed (6)

I believe the answer is:

intact

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'unharmed' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for intact that I've seen before include "Whole and unharmed" , "Unscathed" , "All in one piece" , "Unbroken - sound" , "Flawless" .)

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

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