Plagiarises from Ibsen out of beastliness (6)
I believe the answer is:
steals
'plagiarises' is the definition.
(I've seen this in another clue)
'from ibsen out of beastliness' is the wordplay.
'from' is an anagram indicator (from the letters).
'out of' indicates named letters should be taken away.
'beastliness' with 'ibsen' taken away is 'atless'.
'atless' is an anagram of 'STEALS'.
(Other definitions for steals that I've seen before include "Pilfers" , "Takes property without right or permission" , "Pilfer, filch" , "Robs" , "Purloins" .)