Wash plastic turd? (7)
I believe the answer is:
shampoo
'wash' is the definition.
(shampooing is a kind of washing)
'plastic turd?' is the wordplay.
'plastic' becomes 'sham' (both can mean fake).
'turd?' becomes 'poo'.
'sham'+'poo'='SHAMPOO'
(Other definitions for shampoo that I've seen before include "Carpet/hair cleanser" , "Washer for locks" , "Would Mao shop for this cleaner?" , "treat shock?" , "Hair-cleaner" .)