Quibbler longed to displace editor (6)
I believe the answer is:
pedant
'quibbler' is the definition.
(I've seen this before)
'longed to displace editor' is the wordplay.
I cannot quite understand how this works, but
'editor' could be 'ed' and 'ed' is found in the answer.
The remaining letters 'pant' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
(Other definitions for pedant that I've seen before include "Panted like dogmatist" , "Know-all who insists on strict observance of rules" , "One concerned with excessive detail" , "quibbler" , "Stickler for minor details" .)