Natural to welcome oddly edgy opposite (8)
I believe the answer is:
negative
'opposite' is the definition.
(thesaurus)
'natural to welcome oddly edgy' is the wordplay.
'natural' becomes 'native' (similar in meaning).
'to welcome' indicates putting letters inside (inserted letters are welcomed in).
'oddly' means one should take alternating letters (letters in the odd-numbered positions are used).
The alternating letters of 'edgy' are 'eg'.
'native' enclosing 'eg' is 'NEGATIVE'.
(Other definitions for negative that I've seen before include "Get a vine (anag.)" , "Piece of photographic film" , "Gloom-ridden" , "Less than zero, minus" , "Denying" .)