Money to invest, sterling (7)
I believe the answer is:
capital
I believe this is a double definition.
'money to invest' is the first definition.
(capital can mean money invested in something)
'sterling' is the second definition.
(thesaurus)
(Other definitions for capital that I've seen before include "Madrid, say" , "liquid assets" , "Means" , "What starts this clue" , "Money available to produce interest" .)