A twerp at Oval initially on edge when scoring (7)
I believe the answer is:
agitato
'on edge when scoring' is the definition.
(in an agitated manner, on a musical score)
'a twerp at oval initially' is the wordplay.
'twerp' becomes 'git' (both can mean an annoying person).
'initially' indicates taking the first letters.
The initial letter of 'oval' is 'o'.
'a'+'git'+'at'+'o'='AGITATO'
(Other definitions for agitato that I've seen before include "Musical indication; a go at it (anagram)" , "In restless musical style" , "frenetically scored" , "Restless, wild (mus.)" , "in troubled way" .)