The most common and most likely answer to this crossword clue is the 4 letter word ARCO
A
R
C
O
More clues leading to the result ARCO
Buddy explains!

The straight part
We know that "no longer plucked" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case no longer plucked = arco.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 ARCO mean?
ARCO adverb- A note in string instrument musical notation indicating that the bow is to be used in the usual way, usually following a passage that is played pizzicato.