Guarded (9)
There are a few possibilities for this:
protected
'guarded' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for cautious that I've seen before include "Unadventurous" , "Chary of" , "Keen to avoid danger" , "Careful, shrewd" , "Careful to avoid danger" .)
'guarded' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for defended that I've seen before include "Guarded" , "Protected or supported against attack" , "Protected from harm" , "Represented the accused in a lawsuit" , "Tried to justify" .)
'guarded' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for protected that I've seen before include "Safeguarded, shielded from danger" , "Sheltered" , "Kept from harm" .)