Pip, the dog, is inside tied up (7)
I believe the answer is:
secured
'tied up' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I don't see?
'pip the dog is inside' is the wordplay.
'pip' becomes 'seed' (I've seen this before).
'the dog' becomes 'cur' (cur is a kind of dog).
'is inside' indicates putting letters inside.
'seed' going around 'cur' is 'SECURED'.
Can you help me to learn more?
(Other definitions for secured that I've seen before include "Seized" , "Rescued (anag.)" , "all tied up?" , "this way it's safe" , "attached to lead?" .)