Establish yeti find is fraudulent (8)
I believe the answer is:
identify
'establish' is the definition.
(thesaurus)
'yeti find is fraudulent' is the wordplay.
'is fraudulent' is an anagram indicator.
'yeti'+'find'='yetifind'
'yetifind' is an anagram of 'IDENTIFY'.
(Other definitions for identify that I've seen before include "Sympathise" , "Detect" , "associate" , "Establish who someone is, put name to" , "Recognise, put name to" .)