Ken had luck struggling to control English ass
I believe the answer is:
knucklehead
'english ass' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe there's an association between them I don't understand?
'ken had luck struggling to control' is the wordplay.
'had' is a charade indicator (letters next to each other).
'struggling' indicates anagramming the letters.
'to control' becomes 'head' (heading is a kind of controlling).
'ken'+'luck'='kenluck'
'kenluck' is an anagram of 'knuckle'.
'knuckle'+'head'='KNUCKLEHEAD'
Can you help me to learn more?
(Other definitions for knucklehead that I've seen before include "Idiot -- leaked chunk (anag)" , "Dimwit" , "Oaf" .)