Pledge, overall source of comfort (8,7)
I believe the answer is:
security blanket
'source of comfort' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for security blanket that I've seen before include "child's favourite recourse" , "Embargo on information" , "comforter for child" , "information blackout" , "could relieve child's anxiety" .)