Being abrasive, they put an edge on things (5)
I believe the answer is:
hones
'things' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Perhaps there's a link between them I don't understand?
'being abrasive they put an edge on' is the wordplay.
'being abrasive they put' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'an edge' becomes 'hone' (I've seen this in another clue).
'on' says to put letters next to each other.
's' after 'hone' is 'HONES'.
Can you help me to learn more?
(Other definitions for hones that I've seen before include "Sharpens as on whetstone" , "Perfects, sharpens" , "Sharpens, like knife on stone" , "gets sharp" , "Sharpens on strap, say razor" .)