Jehovah's Witnesses believe that Jesus is divine, however many people have different ideas about what it means to be divine. As you've noted, JWs don't believe that Jesus is God, so what do they mean when they say that Jesus is divine?
From the context of scriptures which use the term, Jehovah's Witnesses interpret "divine" to mean:
"That which belongs to God or pertains to him, that which is godlike or heavenly."
–Insight, Vol. 1, p. 638
Therefore it is a quality of things which relate in some way to God or gods. In Greek, words which convey the idea of divinity even stem from the word "theos" meaning "god."
Colossians 2:9 is very clear about Jesus being divine/having divinity:
"because it is in him that all the fullness of the divine quality dwells bodily."
And this makes sense, because Jesus is described as a god in several places, such as John 1:18, and also because Jesus is from God, in that he is God's son and was sent by God (Galatians 4:4).
Here are some more examples of things which are divine: