The most common and most likely answer to this crossword clue is the 5 letter word LENTO
I've seen this crossword clue in The Times
L
E
N
T
O
More clues leading to the result LENTO
- Fast, or primarily slow
- Slow time of abstinence before Easter egg
- Fast? Old and slow
- Slow and somewhat sullen, too
- One of many popes digesting Holy Writ slowly
- Fast disc played slowly
- Slowly advanced, reaching roundabout?
- Article removed from shed very slowly
- Fast or, at first, slowly?
- Fast Othello finale? On the contrary
Buddy explains!

The straight part
We know that "played slowly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case played slowly = lento.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 LENTO mean?
LENTO noun- A tempo mark directing that a passage is to be played very slowly.
- Very slow.
- Very slowly.