American jerk starts to enrage Englishmen (6)
I believe the answer is:
yankee
'american' is the definition.
(Yankee is an example)
'jerk starts to enrage englishmen' is the wordplay.
'jerk' becomes 'yank' ('yank' can be a synonym of 'jerk').
'starts to' indicates taking the first letters.
The initial letters of 'enrage englishmen' is 'ee'.
'yank'+'ee'='YANKEE'
(Other definitions for yankee that I've seen before include "baseballer?" , "A bet; US Federal soldier" , "Union soldier in the American Civil War" , "Northern soldier in the American Civil War" , "American - bet" .)