Details of some metal fasteners (5,5)
I believe the answer is:
brass tacks
'details' is the definition.
(thesaurus)
'some metal fasteners' is the wordplay.
'some metal' becomes 'brass' (brass is a kind of metal).
'fasteners' becomes 'tacks' (tack is a kind of fastener).
'brass'+'tacks'='BRASS TACKS'
'of' is the link.
(Other definitions for brass tacks that I've seen before include "really mean business" , "Details of practical business (colloq.)" , "Nitty-gritty (got down to)" , "Real business" , "Hard facts" .)