Bar contributing to closing others (5)
I believe the answer is:
ingot
'bar' is the definition.
(thesaurus)
'contributing to closing others' is the wordplay.
'contributing to' indicates the answer is hidden within the clue.
'INGOT' is hidden within 'closing others'.
(Other definitions for ingot that I've seen before include "Unwrought metal cast in a mould" , "Bar of cast metal" , "Bar, brick of metal" , "Seize quickly; steal" , "Block (of steel, gold, etc)" .)