One sports fan has a type of pad that's not finished and well-known for its poor quality (8)
I believe the answer is:
infamous
'pad that's not finished and well-known for its poor quality' is the definition.
I can't tell whether this defines the answer.
'one sports fan has a type' is the wordplay.
'one' becomes 'I' (Roman numeral).
'sports' is an anagram indicator (I've seen 'sport' mean this).
'has a type' becomes 'mous' (I can't explain this - if you can you should give a lot more credence to this answer).
'fan' with letters rearranged gives 'nfa'.
'i'+'nfa'+'mous'='INFAMOUS'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for infamous that I've seen before include "Heinous" , "Notorious, having very bad reputation" , "Notorious, having evil reputation" , "Of evil repute" , "Disreputable" .)