Protected spot protecting dirty dog (6)
I believe the answer is:
secure
'protected' is the definition.
('secure' can be a synonym of 'protected')
'spot protecting dirty dog' is the wordplay.
'spot' becomes 'see' (I've seen this before).
'protecting' indicates putting letters inside.
'dirty dog' becomes 'cur'.
'see' placed around 'cur' is 'SECURE'.
(Other definitions for secure that I've seen before include "Peg" , "Rescue (anag) - make safe" , "Safe and well-protected" , "lock" , "Safe; make fast" .)