Yes, in Germany, one lecturer is in prison (4)
I believe the answer is:
jail
'prison' is the definition.
(jail can mean a prison)
'yes in germany one lecturer' is the wordplay.
'yes in germany' becomes 'ja' ('yes' in German).
'one' becomes 'i' (Roman numeral).
'lecturer' becomes 'l' (abbreviation for lecturer).
'ja'+'i'+'l'='JAIL'
'is in' is the link.
(Other definitions for jail that I've seen before include "detention" , "Cooler" , "Nick" , "Gaol" , "having a stretch here?" .)