Essentially David James, say, lets in goal -- causing feud (8)
I believe the answer is:
vendetta
'feud' is the definition.
(I know that vendetta is a type of feud)
'essentially david james say lets in goal' is the wordplay.
I cannot really see how this works, but
'goal' could be 'end' (both can mean a purpose) and 'end' is located in the answer.
This explanation may well be incorrect...
'causing' acts as a link.
Can you help me to learn more?
(Other definitions for vendetta that I've seen before include "ongoing row" , "Family blood feud" , "Prolonged bitter quarrel" , "Long-running quarrel" , "rivalry" .)