Athletes who get the highest value petrol annoyed with Shell initially (4-8)

'athletes who get the highest' is the definition.
(athletes who jump)

'value petrol annoyed with shell initially' is the wordplay.
'annoyed with' indicates an anagram.
'initially' suggests taking the first letters.
The initial letter of 'shell' is 's'.
'value'+'petrol'='valuepetrol'
'valuepetrol' with its letters anagrammed with 's' gives 'POLE-VAULTERS'.