Strange being, new but not malignant (6)
I believe the answer is:
benign
'not malignant' is the definition.
(I've seen this before)
'strange being new' is the wordplay.
'strange' indicates anagramming the letters.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'being' is an anagram of 'benig'.
'benig'+'n'='BENIGN'
'but' is the link.
(Other definitions for benign that I've seen before include "Innocuous, not malignant" , "Genial; not harmful" , "Meaning no harm" , "Harmless or kind" , "Kindly; not harmful" .)