Backward trader, ogre needing replacement (10)
I believe the answer is:
retrograde
'backward' is the definition.
('retrograde' can be similar in meaning to 'backward')
'trader ogre needing replacement' is the wordplay.
'needing replacement' indicates anagramming the letters (I've seen this in other clues).
'trader'+'ogre'='traderogre'
'traderogre' is an anagram of 'RETROGRADE'.
(Other definitions for retrograde that I've seen before include "turning back" , "Reverse" , "Moving backwards" , "Backward" , "Going back" .)