This is a very nice puzzle–not too hard, but with a bit of an extra challenge regarding the unclued apparatus.
The special instructions read as follows: Six clues contain an extra word, each defining one of the thematic perimeter answers (one being 2 words) which are to be entered clockwise where they will fit. 1A and 1D define the theme. Wickball also comments: Barred but easier than IQ or EV.