Advice on word spacing when playing scrabble

I need some help please!

So me and my girl friend Phoebe were playing a game of scrabble a few weeks back...

We were using The Oxford English dictionary in which to check and clarify words with.

Phoebe wanted to play the word ZOOT. But when looking it up in the dicitionary it comes under :

Zoot Suit

I was very un-happy with allowing this but she claimed it was okay to use ZOOT and not in full as it stated in the dictionary. 

There is no ZOOT, only ZOOT SUIT so my question is.

If a word or phrase has a space between it but is only classed as one word, can it still be used.

As there is no ZOOT i personally don't think it should have been allowed? 

Any help is greatly appreciated!

Thanks

Tim