1: Sailor offers thanks to the British resistance (3)
2: Road leading into dismal swamp (5)
3: Behind and down and out (3)
4: To fight sunburn, he faced pain unflinchingly. (7)
5: Please start to sing at one San Francisco club (7)
6: Goes through ere sixpence circulates (11)
7: New lease isn't required (9)
8: Saint Harry's late news flash (4,5)
12: Alice, Val or 10-across exploit lotus-eating? (2,5,4)
14: User brought back radio part (wrecked sound) to return to use (9)
15: Star Keanu ultimately involved with certain salespeople's backing (9)
18: In the beginning, the first persons found Latin confusing. (7)
19: Choose one chrysanthemum; it's the best that can be done (7)
22: Unscripted part for head librarian (2,3)
23: Hellish center for immigration? (5)
25: Drawing, for example, a bit of a cartoon (3)