Reported bargain that’s hard (5)
I believe the answer is:
steel
'hard' is the definition.
'reported bargain' is the wordplay.
'reported' indicates a 'sounds like' (homophone) clue.
'bargain' becomes 'steal' ('steal' can be a synonym of 'bargain').
'steal' is a homophone of 'STEEL'.
'that's' is the link.
(Other definitions for steel that I've seen before include "Knife-sharpener" , "Structural metal alloy" , "Form of iron" , "brace" , "Hard iron alloy" .)