Appraise, weigh up (6)
I believe the answer is:
assess
This clue is a double definition.
'appraise' is the first definition.
(synonyms)
'weigh up' is the second definition.
(I've seen this before)
(Other definitions for assess that I've seen before include "Estimate the worth or quality of" , "Remedy for all ills" , "Evaluate, estimate" , "Make estimate or appraisal of" , "Estimate, gauge" .)