The most common and most likely answer to this crossword clue is the 4 plus 4 letter word WORD GAME
I've seen this crossword clue in Financial Times
W
O
R
D
G
A
M
E
More clues leading to the result WORD GAME
- Undertaking activity for hangman?
- Make war with dog, setter, in crossword puzzle, say?
- Activity that requires guarantee to be prepared
- This is one way to go to school — what a shame to have to accept it
- Hangman, say, in brawl about lady locking up girl
- Hangman, for one, willing to proceed after brief conversation
Buddy explains!
The straight part
We know that "Activity" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case activity = word game.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.