Meat for haggis, perhaps no longer fresh — a pound (5)
I believe the answer is:
offal
'meat for haggis perhaps' is the definition.
'no longer fresh a pound' is the wordplay.
'no longer fresh' becomes 'off'.
'pound' becomes 'l'.
'off'+'a'+'l'='OFFAL'
(Other definitions for offal that I've seen before include "Edible organs from a butchered animal" , "Bits of waste meat" , "Rubbishy bits of animal flesh" , "Refuse - guts" , "Edible entrails of animals" .)