Learn about vicious dog in stable (6)
I believe the answer is:
secure
'stable' is the definition.
(I've seen this before)
'learn about vicious dog' is the wordplay.
'learn' becomes 'see' (synonyms).
'about' indicates putting letters inside.
'vicious dog' becomes 'cur' (I've seen this before).
'see' enclosing 'cur' is 'SECURE'.
'in' acts as a link.
(Other definitions for secure that I've seen before include "Seize; make fast" , "Safe and well-protected" , "Reliable; firmly fixed" , "Stable" , "Peg" .)