In general, he and others were the death of Charles I (6)

'in general' is the definition.
'ireton' can be an answer for 'general' (I've seen this before). I'm not certain of the 'in' bit.

'he and others were the death of charles i' is the wordplay.
I cannot really understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
'of' could be 'o' and 'o' is present in the answer.
'i' is present in the answer.
The remaining letters 're' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?