1: Create an impression on an envelope? (5)

3: Is Pat suitable? (3)

5: One may be a very long time (3)

7: Hovel revamp ending depression (5)

8: Topics I am prepared to make congenial (9)

10: Add a letter to get the smell of fish (5)

11: First get a French weapon. (3)

12: Nothing we have to pay (3)

13: ...or stuffed with the alternative (5)

1: Those passing the first round see getting D's (5)

2: Is it a chop that's nutty or a nut that's chopped? (9)

3: Diverting a dupe with wrong input (7)

4: Heavy metal group X (4)

6: Explosive device held by one failed candidate (7)

9: How Nero holds one in control (5)

10: And give a little toot! (3)