Clue: Exact revenge finally after account by fellow implicates head of Art (8)
Answer: ACCURATE
Explanation: Definition: Exact

(reveng)**E** [*finally*] *after* **Ac**. (account) *by* **CURT** ("man's name. so "fellow") *implicates* [*head of*] **A**(rt), so **AC-CUR(A)T-E