I'll start with a quibble. If the revealer is going to be HEADOVERHEELS, should there have been multiple Louses (or is that lice?) under each Honcho? I don't really know why I am quibbling, except that quibble is a fun word, because I LOLed when I got the theme. And the theme material entertains. I especially liked NUMEROUNO, TOPBANANA, and SCOUNDREL.
I FWOEd where TOPOm crossed mUSAKA. I didn't know either "Fiddler on ther Roof" star or, to my chagrin, the capital of Zambia. I might have made a better guess than "m," but the "m" got in there somehow and I didn't notice it until I had to track down the error. Derp.
I think the cleverest clue is 66A Split to join (ELOPE) - ha! 16A It grows in the dark (PUPIL) was also good. TUBETOP (strapless summer wear) was a nice blast from the past. Do they still make those? I like the word SPORE, but Horace tells me puffballs are disturbing to encounter in real life. And any mention of APU (Kwik-E-Mart clerk) is always welcome.
In addition to the theme answer itself, there were a couple of NOGOODNIKs in the grid. My least favorite was 65D Shout at a circus (OOH). Also a little weird was 27D Hookup for a tenant: Abbr. (TEL). Does anyone get a telephone hooked up these days? Or is TEL another technology like Nest that I've failed to incorporate into my life?