CATCH PHRASE, ooh, that's such a juicy phrase, eagerly waiting to be mined for crossword wordplay. How about [What's uttered when a detective nabs her quarry?]? Or something that a quarterback yells, to alert his wide receiver?
It took me a few minutes to figure out Margaret's intention because the clue misled me. It's hard enough to follow the sentence fragment "… the opposite of the answer to each starred clue …", and even harder to make the leap that this isn't referring to the full theme answers, only the ends. I was sure that SUMMER FLING was supposed to be the opposite of a CATCHPHRASE somehow.
The basic idea is straightforward: FLING, PASS, PITCH, CHUCK are antonyms of CATCH. What would a more accurate clue be? Perhaps [Popular expression ... or what the opposite of the last words of each answer to each starred clue is?]
Oof, that's hilariously difficult to understand.
What would have generated a sharper a-ha moment, then? Not sure, but since the "opposite" concept feels unrelated to CATCH PHRASE, perhaps NO CATCH [Baseball ump's ruling, and a description of the ends of …] would have been better. That'd have been more of a Monday theme, but that's probably where it belongs.
Solid gridwork, for a debut! I admire Margaret's audacity, intersecting all three themers in a criss-cross pattern. It did necessitate some trade-offs around those intersections. See OVI OPA.
She also worked in more bonuses than the average debut constructor, so much SIMPSON ALICE PAUL PENNILESS WET DISHRAG REMEDIES made possible by the unorthodox themer layout. Again, there were some prices to pay, but only the lower right, with AGA and EES, felt like too much in any one region.
Although the theme concept didn't click strongly, I enjoy it when debut constructors try to twist norms.
ADDED NOTE: A few folks have pointed out that the theme could be construed as opposite = THROW PHRASE, with wacky SUMMER FLING meaning a throw during summertime. That makes more sense!