Mild information let out (6)
I believe the answer is:
gentle
'mild' is the definition.
(similar in meaning)
'information let out' is the wordplay.
'information' becomes 'gen' (gen can informally mean information).
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'let' is an anagram of 'tle'.
'gen'+'tle'='GENTLE'
(Other definitions for gentle that I've seen before include "Kind, not rough" , "amiable" , "Mild and benign" , "that may help angler catch fish" , "Not harsh or violent" .)