Wrong grid one disregarded (7)
I believe the answer is:
ignored
'disregarded' is the definition.
('ignore' can be a synonym of 'disregard')
'wrong grid one' is the wordplay.
'wrong' indicates an anagram.
'grid'+'one'='gridone'
'gridone' is an anagram of 'IGNORED'.
(Other definitions for ignored that I've seen before include "Paid no attention to" , "Disregarded intentionally; failed to consider" , "Left out in the cold" , "overlooked" , "Turned a blind eye to" .)