Notice about dog to tie up (6)
I believe the answer is:
secure
'tie up' is the definition.
(thesaurus)
'notice about dog' is the wordplay.
'notice' becomes 'see' (notice can mean to spot or see).
'about' means one lot of letters goes inside another.
'dog' becomes 'cur' (both can mean a despicable person).
'see' enclosing 'cur' is 'SECURE'.
'to' acts as a link.
(Other definitions for secure that I've seen before include "Firm; safe" , "lock" , "properly restrained" , "Reliable; firmly fixed" , "'Safe, confident (6)'" .)