Remarkable X-ray editor ran is fake (13)
I believe the answer is:
extraordinary
'remarkable' is the definition.
(similar in meaning)
'x-ray editor ran is fake' is the wordplay.
'x ray' becomes 'x-ray' (synonyms).
'is fake' is an anagram indicator.
'xray'+'editor'+'ran'='xrayeditorran'
'xrayeditorran' with letters rearranged gives 'EXTRAORDINARY'.
(Other definitions for extraordinary that I've seen before include "Remarkable - abnormal" , "Phenomenal" , "Exceptional" , "Highly unusual" .)