1 down: Family collected one semi-tropic herb for Americans (8)
Herb for Americans = cilantro, but exactly how everything else fits together is beyond me.
2 down: Feature a themed salute, doubled? (4)
I’m guessing feature = chin, but the rest I’m completely at a loss to explain.
21 down: Putting off shaking bub’s toy? (8)
I’m supposing shaking bub’s toy = rattling, but I can’t explain the other half of the clue.
24 across: Outright authority (4)
The answer, Bass, is a beer, but how outright authority = bass remains a mystery.