Snubbed couple getting put up by relative is a sore point (9)
I believe the answer is:
carbuncle
'snubbed couple getting put up' is the definition.
I can't judge whether this definition defines the answer.
'by relative is a sore point' is the wordplay.
'by' means one lot of letters go next to another.
'relative' becomes 'uncle' (uncle is a kind of relative).
'is a sore point' becomes 'carb' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'uncle' put after 'carb' is 'CARBUNCLE'.
Can you help me to learn more?
(Other definitions for carbuncle that I've seen before include "Sort of boil; a gem" , "Cluster of boils - jewel" , "Large boil-like inflammation - gemstone" , "Severe abscess in the skin" , "growth" .)