Little rise of £1,000? No, £50 (5)

I believe the answer is:

knoll

'little rise' is the definition.
'knoll' can be an answer for 'rise' (I've seen this in another clue). I am not sure about the 'little' bit.

I cannot understand how the rest of the clue works.

(Other definitions for knoll that I've seen before include "Round hillock" , "Little mound" , "Hummock" , "Small round hill" , "Small hill or mound" .)

I've seen this clue in The Guardian.

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