The most common and most likely answer to this crossword clue is the 9 letter word CONSTANCE
I've seen this crossword clue in The Guardian
C
O
N
S
T
A
N
C
E
More clues leading to the result CONSTANCE
- Lady of the Lake
- She loved Oliver and Fagin’s position on things?
- Lady Chatterley’s right-wing position
- Lady of the Lake?
- Lake by Alps with Italian viewpoint
- Lady of the Lake with attitude
- Female Conservative taking particular position
- Chapter on posture in Lady Chatterley, for example
- The Lady of the Lake?
- Changed accents on name of a lake in Germany
Buddy explains!

The straight part
We know that "Lake by Alps" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lake by alps = constance.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.