Dirt, for example, returns round the edge (5)
I believe the answer is:
grime
'dirt' is the definition.
('grime' can be a synonym of 'dirt')
'example returns round the edge' is the wordplay.
'example' becomes 'eg'.
'returns' says the letters should be written in reverse.
'round' means one lot of letters goes inside another.
'the edge' becomes 'rim' (rim is a kind of edge**).
'eg' written backwards gives 'ge'.
'ge' enclosing 'rim' is 'GRIME'.
'for' is the link.
(Other definitions for grime that I've seen before include "Muck" , "an ingrained phenomenon" , "Filth, dirt" , "Soot" , "Dirt, grease" .)