More than father I had been unduly rewarded (8)
I believe the answer is:
overpaid
'been unduly rewarded' is the definition.
I can't judge whether this definition defines the answer.
'more than father i had' is the wordplay.
'more than' becomes 'over' (eg over 100 is more than 100).
'father' becomes 'pa' (pa can mean dad or father).
'i had' becomes 'i'd' (contraction).
'over'+'pa'+'id'='OVERPAID'
Can you help me to learn more?
(Other definitions for overpaid that I've seen before include "Handed over too much money" , "excessively remunerated" , "Too highly rewarded" , "Rewarded too well" , "Given too much money" .)