Military alliance in combat ultimately possesses death instinct (8)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

NATO (military alliance) inside T, HAS (end of combaT, possesses). The Greek word for death, and the God who personified death. Freud wrote about the concept of thanatos and eros being the instincts for death and life, bringing the word into present day usage.