Appraise or gauge (8)
I believe the answer is:
evaluate
I believe this is a double definition.
'appraise' is the first definition.
(I know that appraise can be written as evaluate)
'gauge' is the second definition.
(I've seen this in another clue)
(Other definitions for evaluate that I've seen before include "Make an assessment of, determine worth" , "Reckon worth of" , "'Assess, appraise (8)'" , "Judge the worth of something" , "Make an assessment of, measure" .)