The most common and most likely answer to this crossword clue is the 5 plus 5 letter word PIANO STOOL
I've seen this crossword clue in Financial Times
P
I
A
N
O
S
T
O
O
L
More clues leading to the result PIANO STOOL
- . Somewhere to sit is optional, so be prepared
- Player positioned here, also with option to adjust?
- Support for key person in soap playing instrument
- What sustained Liberace playing apt solo No. 1
- Applied soap lotion can control rise and fall at the keyboard
- Furniture for arranging notes?
- Seat in front of lots of flats etc.
- Monk would have sat here quietly, Trappists ultimately needing vice, say?
Buddy explains!

The straight part
We know that "What sustained Liberace" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what sustained liberace = piano stool.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.