FISH
Each answer contains a type of fish.
1. The only one
 Sole
2. Each of the lines in which light may seem to stream from the sun
 Ray
3. Partially burn
 Char
4. Friend of Hergé's Tintin
 Captain Haddock
5. First Minister of Scotland (dated March 2021)
 Nicola Sturgeon
6. English stand-up comedian and writer whose early work included a comedy double act with Stewart Lee
 Richard Herring
7. Find fault continually about trivial matters
 Carp
8. To sit on or near the edge of something
 Perch
9. Dad's Army character
 Pike
10. A hairstyle, popular in the 1980s, in which the hair is short on the sides and top and long at the back.
 Mullet