Disregard information about displaced Celt (7)
I believe the answer is:
neglect
'disregard' is the definition.
('neglect' can be a synonym of 'disregard')
'information about displaced celt' is the wordplay.
'information' becomes 'gen' (gen is a kind of information).
'about' says the letters should be written in reverse.
'displaced' indicates anagramming the letters.
'gen' in reverse letter order is 'neg'.
'celt' anagrammed gives 'lect'.
'neg'+'lect'='NEGLECT'
(Other definitions for neglect that I've seen before include "slight" , "Failure to show care" , "Disregard or fail to care for" , "Fail to look after (something)" , "Treat carelessly" .)