The most common and most likely answer to this crossword clue is the 10 letter word UNDULATION
I've seen this crossword clue in The Daily Telegraph
U
N
D
U
L
A
T
I
O
N
Buddy explains!

The straight part
We know that "Wave" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wave = undulation.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 UNDULATION mean?
UNDULATION noun- An instance or act of undulating.
- A wavy appearance or outline; waviness.
- A tremulous tone produced by a peculiar pressure of the finger on a string.
- A wavelike curve; a smooth and regular rise and fall.
- A wavelike motion of the air; electromagnetic radiation.
- A feeling as if of an undulatory motion about the heart.
- The distinctive motion of the matter within an abscess on being pressed when it is ripe for opening.