Very old — and value in it misplaced (12)
I believe the answer is:
antediluvian
'very old' is the definition.
(I've seen this before)
'and value in it misplaced' is the wordplay.
'misplaced' indicates an anagram.
'and'+'value'+'in'+'it'='andvalueinit'
'andvalueinit' is an anagram of 'ANTEDILUVIAN'.
(Other definitions for antediluvian that I've seen before include "Very old (before the Flood)" , "before the water's bubbled up" , "Very old-fashioned (from before the Flood?)" , "Before the flood; ancient" .)