I felt that initially extravagant need to pay (3)
I believe the answer is:
owe
'need to pay' is the definition.
(I've seen this before)
'i felt that initially extravagant' is the wordplay.
'i felt' becomes 'ow' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'that initially' says to take the initial letters.
The initial letter of 'extravagant' is 'e'.
'ow'+'e'='OWE'
Can you help me to learn more?
(Other definitions for owe that I've seen before include "Have a debt to (someone)" , "have favours to return" , "Need to pay" , "Be indebted" , "Be obliged to pay" .)