Increase the loan (7)
I believe the answer is:
advance
This clue is a double definition.
'increase' is the first definition.
(I know that advance is a kind of climb)
'loan' is the second definition.
(advancing is a kind of loaning)
'the' is the link.
(Other definitions for advance that I've seen before include "Move forwards" , "Early" , "Bring forward" , "capital" , "Payment ahead of due date (1'7)" .)