One well overdue to be cut off (7)
I believe the answer is:
isolate
'be cut off' is the definition.
(I've seen this before)
'one well overdue' is the wordplay.
'one' becomes 'i' (roman numeral).
'well' becomes 'so' (I've seen this in other clues).
'overdue' becomes 'late' (similar in meaning).
'i'+'so'+'late'='ISOLATE'
'to' acts as a link.
(Other definitions for isolate that I've seen before include "put away?" , "Ostracise" , "Put into quarantine" , "Separate and keep away from other people" , "Place or set apart" .)