German agreement to cut off tail of dodgy car (6)
I believe the answer is:
jalopy
'car' is the definition.
(jalopy is a kind of car)
'german agreement to cut off tail of dodgy' is the wordplay.
'german agreement' becomes 'ja' (I've seen this in other clues).
'to cut off' becomes 'lop' (I've seen this before).
'tail of' says to take the final letters.
The last letter of 'dodgy' is 'y'.
'ja'+'lop'+'y'='JALOPY'
(Other definitions for jalopy that I've seen before include "Dilapidated car (colloq.)" , "Rundown old car" , "Old vehicle" , "Old and unreliable car" , "Clapped-out car" .)