Pitch took hold on intellect forfeiting a commanding lead (7)
I believe the answer is:
bitumen
'pitch' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for bitumen that I've seen before include "material that surfaces" , "Road's topping" , "Road-surfacing material" , "coverage on the streets?" , "Asphalt" .)