When a swelling's risen, increase the price (4,2)
I believe the answer is:
bump up
'price' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how one could define the other.
'when a swelling's risen increase' is the wordplay.
I cannot really see how this works, but
'risen' could be 'up' (similar in meaning) and 'up' is located in the answer.
'increase' could be 'bump' (I've seen this in another clue) and 'bump' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'the' is the link.
Can you help me to learn more?
(Other definitions for bump up that I've seen before include "Raise (prices)" , "hike" .)