Cleaner put off by chap (9)
I believe the answer is:
detergent
'cleaner' is the definition.
(chemical that cleans)
'put off by chap' is the wordplay.
'put off' becomes 'deter' (both can mean to discourage).
'by' means one lot of letters go next to another.
'chap' becomes 'gent' (both can mean a man).
'deter'+'gent'='DETERGENT'
(Other definitions for detergent that I've seen before include "Soluble cleansing agent" , "Synthetic cleaning substance for washing machines" , "help with the washing-up" , "Cleansing solvent" , "Cleaning product" .)