Cut off from detective's sidekick (12)
I believe the answer is:
disassociate
'cut off' is the definition.
Both the answer and definition are verbs in their base form.
Maybe there's an association between them I don't understand?
'detective's sidekick' is the wordplay.
I cannot really see how this works, but
'detective's' could be 'dis' (Detective Inspector) and 'dis' is found within the answer.
The remaining letters 'associate' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'from' is the link.
Can you help me to learn more?
(Another definition for disassociate that I've seen is " Disconnect, separate".)