Cold, old, quiet club (4)
I believe the answer is:
cosh
'club' is the definition.
(I know that cosh is a type of bludgeon)
'cold old quiet' is the wordplay.
'cold' becomes 'c' (abbreviation, eg on taps).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'c'+'o'+'sh'='COSH'
(Other definitions for cosh that I've seen before include "Blunt instrument" , "Heavy stick-like weapon" , "Truncheon, bludgeon" , "Thick heavy stick as a weapon" , "Club used as a weapon" .)