Come to a hill (6)
I believe the answer is:
amount
'come' is the definition.
(I know that come can be written as amount)
'a hill' is the wordplay.
'hill' becomes 'mount' (I've seen this before).
'a'+'mount'='AMOUNT'
'to' is the link.
(Other definitions for amount that I've seen before include "A quantity or total of anything" , "Sum of money" , "value" , "Total or extent" , "Supply" .)