Paid a pound for a hammer (5)
I believe the answer is:
gavel
'a hammer' is the definition.
(gavel is a kind of hammer)
'paid a pound' is the wordplay.
'paid' becomes 'gave' ('give' can be a synonym of 'pay').
'a pound' becomes 'l'.
'gave'+'l'='GAVEL'
'for' is the link.
(Other definitions for gavel that I've seen before include "Mason's hammer" , "Judge's hammer" , "Small hammer" , "Chairman's hammer" , "Small mallet" .)