Safe spot to catch dog (6)
I believe the answer is:
secure
'safe' is the definition.
(similar in meaning)
'spot to catch dog' is the wordplay.
'spot' becomes 'see' (both can mean to notice or observe).
'to catch' is an insertion indicator.
'dog' becomes 'cur' (a cur is an aggressive or scruffy dog).
'see' placed around 'cur' is 'SECURE'.
(Other definitions for secure that I've seen before include "Firmly in place - free from danger" , "Free from danger or risk" , "land" , "'Safe, confident (6)'" , "Firm; safe" .)