I don't know about the clause.. I know it has never been excercised though as any uproar towards the EU is news-worthy enough...
I can imagine it in place, mainly for farmers. Farming is the highest costplace of the EU and a lot of farmers cannot compete with richer countries both in the EU and other developed nations like the US.
So it is entirely possible that they have a clause for them, though the EU usually supports farmers with guaranteed prices and subsidys.
I certainly hope that the US will not put this clause through... I cannot imagine that their own market is larger then the rest of the world buying US steel. So if all the countries would switch it would end up with more job-losses in the end (IF the external steel market is greater then the internal)
The Doctor will see you now
Promoting Lesbianism --> 
