Notice German with grant (5)
I believe the answer is:
admit
'grant' is the definition.
(grant can mean to agree or admit something)
'notice german with' is the wordplay.
'notice' becomes 'ad' (both can mean an advertisement).
'german with' becomes 'mit' ('with' in German).
'ad'+'mit'='ADMIT'
(Other definitions for admit that I've seen before include "Agree to the truth" , "Confess; allow in" , "Let in - concede" , "Recognise" , "receive" .)