Paying for light blue (8,5)
I believe the answer is:
shouting match
'blue' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'paying for light' is the wordplay.
'paying for' becomes 'shouting' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'light' becomes 'match' (match is a kind of light).
'shouting'+'match'='SHOUTING MATCH'
Can you help me to learn more?
(Other definitions for shouting match that I've seen before include "Loud quarrel (colloq.)" , "row" .)