The crossword answer for the clue “when one can see an adder” is usually “SUMMER” (6 letters).

Why “SUMMER” fits

  • In British English, an adder is a type of snake that is most visible and active in summer , which makes the clue a cryptic-style reference to the season.
  • Many crossword clue databases list “SUMMER” among common answers associated with adder (as in the snake rather than a calculator).

Extra tip for similar clues

  • When a clue mentions an animal plus a vague time phrase like “when one can see …” , think of:
    • The animal’s active season (e.g., summer, spring).
* Common crossword wordplay linking **snakes** to warm weather or sunbathing on heathland.

TL;DR: For “when one can see an adder” , fill in SUMMER.

Information gathered from public forums or data available on the internet and portrayed here.