The most common and most likely answer to this crossword clue is the 6 letter word LURKED
I've seen this crossword clue in The Daily Telegraph
L
U
R
K
E
D
Buddy explains!

The straight part
We know that "Lay in wait" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lay in wait = lurked.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.
What does LURKED mean?
LURKED verb- To remain concealed in order to ambush.
- To remain unobserved.
- To hang out or wait around a location, preferably without drawing attention to oneself.
- To view an internet forum without posting comments.
- To saddle (a person) with an undesirable task or duty.