I buy a bale of "grass hay" from a local farmer. (Timothy hay is a type of grass hay.) I doubt that there is any clover in it, but when I pull it apart to put in Idgie's cage, I just give her the hay. If a weed or something is in there, I just pull it out. But it doesn't happen often.
So if they just mean that there is the occasional clover in it, I wouldn't worry about it. (You might want to do a search on clover b/c it might be okay for a chin--I just don't remember.) Did you get a chance to look at it? Do they feed it to horses--if so, that would be good for chins.
I pay the same amount for an entire bale that Idgie couldn't even eat half of in a year compared to one small bag that wouldn't last a week or two. It's definitely worth looking into more.