Prize or treasure (5)
I believe the answer is:
value
I believe this is a double definition.
'prize' is the first definition.
(I know that prize can be written as value)
'treasure' is the second definition.
(I know that treasure can be written as value)
'or' acts as a link.
(Other definitions for value that I've seen before include "Hold in high regard" , "Esteem" , "Appreciate" , "Assess, put a price on" , "Estimate the worth of" .)