In Luke, perhaps, it's uncharacteristic (6)
I believe the answer is:
unlike
'uncharacteristic' is the definition.
(thesaurus)
'in luke perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'in'+'luke'='inluke'
'inluke' is an anagram of 'UNLIKE'.
'it's' is the link.
(Other definitions for unlike that I've seen before include "Not similar or comparable to" , "Dissimilar" , "Different from" .)