The most common and most likely answer to this crossword clue is the 7 letter word SOLITON
I've seen this crossword clue in The Guardian
S
O
L
I
T
O
N
Buddy explains!
The straight part
We know that "Lots? No, one wave" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lots? no, one wave = soliton.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 SOLITON mean?
SOLITON noun- A self-reinforcing pulse or travelling wave caused by any non-linear effect (found in many physical systems).