Choke on good silver (3)
I believe the answer is:
gag
'choke on' is the definition.
(thesaurus)
'good silver' is the wordplay.
'good' becomes 'g' (abbreviation).
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'g'+'ag'='GAG'
(Other definitions for gag that I've seen before include "Put a muzzle on the joke" , "Prevent free expression" , "Choke; joke" , "A palindromic joke or muzzle" , "Muzzle in palindrome form" .)