12 across: Frequent flyer strikes trouble with online trade (5)
I know the answer is e-tail = online trade; I just don’t know why (although trouble has an e as its tail).
7 down: Top crawler disrupts bent magic (8)
Here, the answer is wizardry = magic. The rest?
4 down: In desert, left for love, make love to actor (6, 6)
Actor = Marlon Brando, but what goes on with the rest of it?
17 down: Damned thug gives no end of trouble (8)
I was never gonna get this one, and now that I’ve consulted dictionary.com to make sure, I’m still none the wiser on how to begin explaining why ballyhoo is the answer.