Quietly riles about an implement (6)
I believe the answer is:
pliers
'an implement' is the definition.
(pliers is a kind of implement)
'quietly riles about' is the wordplay.
'quietly' becomes 'p' (p for piano and quiet**).
'about' is an anagram indicator.
'riles' anagrammed gives 'liers'.
'p'+'liers'='PLIERS'
(Other definitions for pliers that I've seen before include "Workmen's tools" , "Hand tool used for gripping" , "taxi-drivers, say" , "Small tool for gripping things" , "Tool with jaws for gripping small objects" .)