Cleaner put off dope by tenor (9)
I believe the answer is:
detergent
'cleaner' is the definition.
(chemical that cleans)
'put off dope by tenor' is the wordplay.
'put off' becomes 'deter' (both can mean to discourage).
'dope' becomes 'gen' (both can mean information).
'by' is a charade indicator (letters next to each other).
'tenor' becomes 't'.
'deter'+'gen'+'t'='DETERGENT'
(Other definitions for detergent that I've seen before include "Synthetic cleaning substance for washing machines" , "Cleansing substance used for washing clothes" , "Soluble cleansing agent" , "Get tender (anag)" , "Soluble cleanser" .)