Epic novel about King of Ireland is first rate and more expensive (7)
I believe the answer is:
pricier
'more expensive' is the definition.
('pricy' can be similar in meaning to 'expensive')
'epic novel about king of ireland is first rate' is the wordplay.
'novel' indicates anagramming the letters (letters in a new or novel order).
'about' means one lot of letters goes inside another.
'king of ireland' becomes 'ri' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'is first' says to take the initial letters.
The initial letter of 'rate' is 'r'.
'epic' anagrammed gives 'pcie'.
'pcie' going around 'ri' is 'pricie'.
'pricie'+'r'='PRICIER'
'and' acts as a link.
Can you help me to learn more?
(Another definition for pricier that I've seen is " More expensive".)