Harmless information let loose (6)
I believe the answer is:
gentle
'harmless' is the definition.
(thesaurus)
'information let loose' is the wordplay.
'information' becomes 'gen' (gen is a kind of information).
'loose' indicates anagramming the letters (letters are loosened from their original positions).
'let' is an anagram of 'tle'.
'gen'+'tle'='GENTLE'
(Other definitions for gentle that I've seen before include "Clement" , "Moderate, quiet; a maggot" , "'Mild, soft, tender (6)'" , "Not harsh or violent" , "'Do not go . . . . . . into that good night' (Dylan Thomas)" .)