One nasty guy cutting blockbuster in pieces (8)
I believe the answer is:
episodic
'in pieces' is the definition.
(in separate pieces or episodes)
'one nasty guy cutting blockbuster' is the wordplay.
'one' becomes 'i' (Roman numeral).
'nasty guy' becomes 'sod' (sod can mean a nasty or annoying person).
'cutting' is an insertion indicator (some letters cut their way into a word).
'blockbuster' becomes 'epic' (epic film).
'i'+'sod'='isod'
'isod' inserted into 'epic' is 'EPISODIC'.
(Other definitions for episodic that I've seen before include "Intermittent" , "Divided into tenuously related parts" , "Discursive" , "Occurring irregularly or in instalments" , "Occurring irregularly - is copied accordingly" .)