Politicians invested in large universities with millions in one-off payment (4,3)
I believe the answer is:
lump sum
'one-off payment' is the definition.
(a lump sump is a single payment)
'politicians invested in large universities with millions' is the wordplay.
I cannot really understand how this works, but
'politicians' could be 'mps' (Members of Parliament) and 'mps' is present in the answer.
'large' could be 'l' (eg in clothes sizes) and 'l' is found in the answer.
'universities' could be 'uu' (two abbreviations for university) and 'uu' is found within the remaining letters.
'millions' could be 'm' (abbreviation) and 'm' is present in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'in' is the link.
Can you help me to learn more?
(Other definitions for lump sum that I've seen before include "Whole payment" , "Large single payment" , "chunk of bread?" , "one lot of money" , "Single amount of money" .)