I'd go for TWO also as over could be Too as in Too many and heard is "sounds like" and the whole thing tenuously could be Two-time. Don't you just hate clues like this?
Julie The added problem is that letters from other clues don't help...T is from Lightning and O is from Forest leaving the middle letter.
I'm going to go for Two only because I am in a hurry as the Tour cyclists and their entourage are coming through my village later this morning and then the Grand Prix and the tennis!