Bar stopping others taking part (5)
I believe the answer is:
ingot
'bar' is the definition.
(thesaurus)
'stopping others taking part' is the wordplay.
'taking part' indicates a hidden word.
'INGOT' is hidden within 'stopping others'.
(Other definitions for ingot that I've seen before include "Cast metal brick" , "Piece of cast metal" , "Metal casting" , "Metallic bar" , "Piece of precious metal" .)