Holler about flat I renovated in artful style (8)
I believe the answer is:
craftily
'in artful style' is the definition.
(I know this)
'holler about flat i renovated' is the wordplay.
'holler' becomes 'cry' (I've seen this in another clue).
'about' is an insertion indicator.
'renovated' indicates an anagram.
'flat'+'i'='flati'
'flati' anagrammed gives 'aftil'.
'cry' placed around 'aftil' is 'CRAFTILY'.
(Other definitions for craftily that I've seen before include "In a cunning way" , "Cunningly, deceitfully" .)