effective, good, great, powerful, real
credible
the ultimate (esp. BrE)
Defenders of the death penalty regard it as the ultimate deterrent.

nuclear
They stressed the need for an independent nuclear deterrent.

strategic (esp. AmE)

act as, be, provide
a punishment that will act as a deterrent to other offenders

effect
They were arguing about the deterrent effect of nuclear weapons.

as a deterrent
The bodies of executed criminals were hung on the city gates as a deterrent.

deterrent against
a deterrent against cheating

deterrent for
There is no effective deterrent for these young criminals.

deterrent to
a deterrent to crime
a deterrent to all but the most determined attacker

Deterrent is used with these nouns:
effect