Dust off fastener (4)
I believe the answer is:
stud
'fastener' is the definition.
(I've seen this before)
'dust off' is the wordplay.
'off' indicates an anagram.
'dust' with letters rearranged gives 'STUD'.
(Other definitions for stud that I've seen before include "Stallion; rivet" , "Knob; fastener; boss" , "Ladies' man?" , "Decorative round-headed nail" , "who believes he can keep it up" .)