Influence is held by established kind of writer (8)
I believe the answer is:
essayist
'kind of writer' is the definition.
(I've seen this before)
'influence is held by established' is the wordplay.
'influence' becomes 'say' (I've seen this in other clues).
'held by' indicates putting letters inside.
'established' becomes 'est' (I've seen this in other clues).
'say'+'is'='sayis'
'sayis' going within 'est' is 'ESSAYIST'.
(Other definitions for essayist that I've seen before include "Writer such as Addison" , "The venturer" , "Writer of shorter pieces" , "Writer of pieces on various subjects" , "Writer of short literary pieces" .)