Let nobody have dealings with one as unpunctual as this (7)
I believe the answer is:
isolate
'let' is the definition.
The answer and definition can be both related to change as well as being verbs in their base form.
Maybe there's a link between them I don't understand?
'nobody have dealings with one as unpunctual as this' is the wordplay.
I cannot really understand how this works, but
'one' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
'unpunctual' could be 'late' (similar in meaning) and 'late' is located in the answer.
The remaining letters 'is' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for isolate that I've seen before include "split up" , "Keep apart" , "put away?" , "Place in seclusion" , "Set apart from others" .)