Ok, well I'll tell you my answer. I worked on the fact that the words "semi" and "demi" also mean "half". Then the clue could be read:
Half half: ha
Half demi: de
Half (of) half semi: s
HADES
I was concerned that I was going a step too far with the above, but now I think that if there are two answers, then maybe it's not such a good clue after all.
I did come up with another version, (which my girlfriend though was funnier!), which was:
Semi half semi demi hemi demi semi god (5).