Stop fellow getting soap powder (9)
I believe the answer is:
detergent
'soap powder' is the definition.
'detergent' can be an answer for 'soap' (thesaurus). I am not sure about the 'powder' bit.
'stop fellow' is the wordplay.
'stop' becomes 'deter' (to deter behaviour is to stop it).
'fellow' becomes 'gent' (synonyms).
'deter'+'gent'='DETERGENT'
'getting' acts as a link.
Can you help me to learn more?
(Other definitions for detergent that I've seen before include "Cleaning product" , "cleaner" , "Cleansing solvent" , "Cleansing substance used for washing clothes" , "Synthetic cleaning substance for washing machines" .)