Allow back in to study with German (7)
I believe the answer is:
readmit
'allow back in' is the definition.
'study with german' is the wordplay.
'study' becomes 'read' ('read' can be a synonym of 'study').
'with german' becomes 'mit'.
'read'+'mit'='READMIT'
'to' acts as a link.
(Other definitions for readmit that I've seen before include "Allow back into" , "Again accept" , "Let back in" , "Dear Tim (anag.)" , "Let in a second time" .)