Rump (6)
'rump' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for behind that I've seen before include "support" , "Responsible for" , "Hidden by; in arrears" , "Astern" , "Running late" .)
'rump' is the definition.
(I know that rump can be written as posterior)
This is all the clue.
(Other definitions for posterior that I've seen before include "Further back; bottom" , "later" , "Behind" , "Hindquarters" , "Stern" .)