Re-use old material (6)
I believe the answer is:
rehash
're-use old material' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rehash that I've seen before include "Serve up old ideas" , "Use again (changing little)" , "Reuse (old ideas) with little improvement" , "Recycled material" , "Same material, different mix" .)