Request quiet guide (5)
I believe the answer is:
plead
'request' is the definition.
(I've seen this before)
'quiet guide' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano').
'guide' becomes 'lead' ('lead' can be a synonym of 'guide').
'p'+'lead'='PLEAD'
(Other definitions for plead that I've seen before include "advocate in court" , "Argue (a position in court)" , "Present an argument in court" , "Supplicate" , "Appeal earnestly" .)