Strangles Morse, ultimately one of five English detectives with self-control (6,9)

'strangles morse ultimately' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'one of five english detectives with self-control' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
'english' could be 'e' (abbreviation) and 'e' is found within the answer.
'detectives' could be 'dis' (Detective Inspectors, DIs) and 'dis' is located in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?