1: Create an impression on an envelope? (5)
2: It comes to a point everyone heard (3)
3: Horse fly's, um, retreating (7)
4: Exercise is right for a one-time actor (9)
5: April keeps providing material for a poet (5)
6: Go over the same ground? (7)
7: Plunges about in State's evidence (5)
8: English scenes reproduced for 'Nature' (7)
12: No French islands for the other Dr. Crane (5)
15: This is truncated, or the end's off (9)
17: Like powerful uncle in Indian state? (5)
18: Climactic age opal tossed (7)
19: United States taken in by tax he prepared to squander (7)
21: Too old for insurance protection without a cap (7)
23: Object of thinking without pen (5)
25: Note found in prison is swell (5)
26: Writer deserts pea-green match (5)