Spot the dog is in, free from danger (6)
I believe the answer is:
secure
'free from danger' is the definition.
(I've seen this in another clue)
'spot the dog is in' is the wordplay.
'spot' becomes 'see' (both can mean to notice or observe).
'the dog' becomes 'cur' (a cur is an aggressive or scruffy dog).
'is in' means one lot of letters goes inside another.
'see' going around 'cur' is 'SECURE'.
(Other definitions for secure that I've seen before include "Fix; safe" , "Safe; fixed" , "Stable" , "Safe and well-protected" , "'Safe, confident (6)'" .)