Spike has debts? Apparently, but they're not genuine! (8)
I believe the answer is:
spurious
'not genuine' is the definition.
(I've seen this before)
'spike has debts?' is the wordplay.
'spike has' becomes 'spur' (I can't justify this - if you can you should believe this answer much more).
'debts?' becomes 'IOUs' (promises to pay debts).
'spur'+'ious'='SPURIOUS'
'apparently but they're' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for spurious that I've seen before include "Forged" , "Plausible, but false" , "deceitful!" , "Bogus" , "Not genuine or authentic" .)