Puts off till a later time (9)
(Other definitions for postpones that I've seen before include "Puts off till another time" , "Holds over to another time" .)
'puts off till a later time' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for defers that I've seen before include "'Holds over, postpones (6)'" , "Yields to another's wish" , "Puts off or gives way to another" , "Yield to another's wish" , "Gives precedence (to)" .)