Old money football club's managed to invest (5)
I believe the answer is:
franc
'old money' is the definition.
(I've seen this before)
'football club's managed to invest' is the wordplay.
I cannot really see how this works, but
'managed' could be 'ran' (I've seen this in another clue) and 'ran' is located in the answer.
'football club' could be 'fc' and 'fc' is found within the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for franc that I've seen before include "for laying out in Luxembourg" , "Historic currency" , "money abroad" , "Foreign capital" , "I'm accepted in Basle" .)