Partial deliveries coming back by rail (6)
I believe the answer is:
revile
'rail' is the definition.
(I know that rail can be written as revile)
'partial deliveries coming back' is the wordplay.
'partial' says the answer is hidden in the clue.
'coming back' says the letters should be written in reverse.
'eliver' can be found hidden inside 'deliveries'.
'eliver' reversed gives 'REVILE'.
'by' acts as a link.
(Other definitions for revile that I've seen before include "Upbraid, berate" , "Vilify" , "Abuse verbally" , "Criticise - abuse" , "Abusively criticise" .)