2 Down - Sweetheart in love cheers demoiselles. I have O-O-A-A. (I thought of ooh-la-la but that is hyphenated, needs an H instead of an O and doesn't make sense in relation to the rest of the clue.)
Love is the score in tennis for 0 :-)
Yet would never have found this word- all the posters here are genii :-) for sure!!
Never know Dona was sweetheart either- lean something new every day ;-) http://www.thefreedictionary.com/order+Odonata
I'd always thought of the word as Donna (probably from the Spanish) I've got a vague memory of an old Music Hall song called "Never introduce your Donna to a chum"