Stop being led by snake oil industry product (7)
I believe the answer is:
Here is my best explanation:
'oil industry product' is the definition.
'stop being led by snake' is the subsidiary indication.
'stop' becomes 'halt' (halting is a kind of stopping).
'being led by' means one lot of letters go next to another.
'snake' becomes 'asp' (asp is a kind of snake).
'halt' put after 'asp' is 'asphalt'.
(Other definitions for asphalt that I've seen before include "Mixture of tar and gravel used in road surfaces", "Substance used in roofs and roads", "A road surfacing", "Road surface material", "Material for covering roads", "Surface material", "Bitumen", "Road-buiding material", "A road-surfacing material" and "Bituminous road dressing".)