During chorus, trumpeters play strings (5)
I believe the answer is:
strum
'play strings' is the definition.
(as in strumming a guitar)
'during chorus trumpeters' is the wordplay.
'during' says the answer is hidden in the clue.
'STRUM' is hidden in the letters of 'chorus trumpeters'.
(Other definitions for strum that I've seen before include "Sweep fingers over strings" , "Casually play (on a stringed instrument)" , "Play idly on guitar etc" , "Pluck the strings idly" , "Play stringed instrument with sweep of hand" .)