Thank goodness for Google. Without it, there's no way I would ever have finished this puzzle. But it took me so long to solve it that I am completely exhausted, so this will be brief.
There actually wasn't that much to Google, but some of the answers I found gave me a toehold.
Only a couple of gimmes in the puzzle:
1A: Be an agent of (act for). Don't know why I guessed that, but it was right.
15A: Hawaiian "thank you" (mahalo). That's a word that we used often when we were there. The locals were so friendly and so helpful. We're looking forward to experiencing the spirit of aloha once again...just three weeks from tomorrow. And mahalo to those who have agreed to be guest bloggers...Robert, Rick, Howard and Dave. There are still Monday and Tuesday slots available. Let me know if you're interested in filling in one or two days.
22A: Grooming brand introduced in 1977 (Atra).
37A: "__ Peak" (1997 Pierce Brosnan film) (Dante's). Didn't see it, but I'd heard of it.
1D: Unscrupulous (amoral)...that's probably more like a good guess, since I had the AM in place.
3D: Fights with knights (the Crusades)...and with only the TH.
23D: Ancient meeting places (agoras)...a word I know only from crosswords.
There were some good long answers.
33A: Constellation seen on the flags of Australia, Samoa and Papua New Guinea (Southern Cross). This is one of the answers I got from Google. I know two constellations, Ursa Major and Ursa Minor. If I can remember this one, I'll know three.
38A: Parliamentary address? (Madame Speaker).
10D: Skin pics? (cheesecake). Sorry, no visuals here. Liked the similar clue for 12D: Skin pic? (tat). I have actually heard people refer to their tattoos in the abbreviated form.
25D: Cleaning product that may be useful after a party (spot remover).
There were several words that don't appear often in puzzles. 18A: Catholic (eclectic); 43A: Striking figures (picketers)...clever clue, that one; 54A: Void (abrogate); 59A: Opposite of diminish (heighten); 2D: Pantheon heads? (capita)...another clever one; 8D: Scale developer (Richter); 39D: Speak explosively in anger (sputter)...I associate that more with cartoon characters, like Daffy Duck; 40D: Dumps (pig pens); and 45D: Bad-tempered (snarly)...me, by the time I finished this puzzle.
29D: Short, close-fitting jacket (hug me tight). Have never heard that expression, and it isn't in my dictionary. Too tired to Google it, but if someone has, please let me know what turns up.
Liked 61A: Cardinals' gathering place (St. Peter's). I tried to think of the name of the stadium where the Cardinals played their home games.
I'm off to bed. Here's the grid.
...and I'll see you tomorrow.