Noble government peer endlessly promises to pay (8)
I believe the answer is:
glorious
'noble' is the definition.
(I've seen this before)
'government peer endlessly promises to pay' is the wordplay.
'government' becomes 'g'.
'peer' becomes 'lord' (I've seen this before).
'endlessly' means to remove the last letter.
'promises to pay' becomes 'ious' (more than one iou).
'lord' with its final letter removed is 'lor'.
'g'+'lor'+'ious'='GLORIOUS'
(Other definitions for glorious that I've seen before include "'Magnificent, splendid (8)'" , "Illustrious" , "with honour" , "Strikingly beautiful or impressive" , "Wonderful" .)