Review fake nails, say (8)
I believe the answer is:
analysis
'review' is the definition.
(thesaurus)
'fake nails say' is the wordplay.
'fake' indicates anagramming the letters (I've seen this in other clues).
'nails'+'say'='nailssay'
'nailssay' is an anagram of 'ANALYSIS'.
(Other definitions for analysis that I've seen before include "See 15" , "Examination of structure (eg of psyche)" , "Criticism" , "Study of mind" , "Determination" .)