Against fastening on edge, like some earrings? (4-2)
I believe the answer is:
clip-on
'like some earrings?' is the definition.
(I've seen this in another clue)
'against fastening on' is the wordplay.
'against' is a charade indicator (letters next to each other).
'fastening' becomes 'clip' (clip is a kind of fastening).
'clip' put next to 'on' is 'CLIP-ON'.
'edge' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for clip-on that I've seen before include "Attachable" , "Gripping accessory" , "Easily removable tie" , "Kind or earring or bow tie" , "Attached like a bow tie, for example" .)