Enjoy increase in value (10)
I believe the answer is:
appreciate
This clue is a double definition.
'enjoy' is the first definition.
(I've seen this before)
'increase in value' is the second definition.
(I've seen this in another clue)
(Other definitions for appreciate that I've seen before include "Increase in value" , "Treasure" , "Grow in value" , "Enjoy" , "gain in value" .)