Clerical work done by a metal worker (6)
I believe the answer is:
filing
This clue is a double definition.
'clerical work' is the first definition.
'done by a metal worker' is the second definition.
(a particle made by someone working with metal)
(Other definitions for filing that I've seen before include "Arranging documents methodically" , "Recording" , "Clerical work (done by metal workers?)" , "- - cabinet" .)