Give permission (7)
'give permission' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for consent that I've seen before include "Agree (to do something)" , "Agree(ment)" , "Give approval" , "Give permission for something" , "Say yes to something" .)
(Other definitions for assent that I've seen before include "Say yes" , "Acquiescence" , "Agree, acquiesce" , "Nod" , "Give consent" .)