Value ship upon high seas (6)
I believe the answer is:
assess
'value' is the definition.
(I know that value can be written as assess)
'ship upon high seas' is the wordplay.
I cannot really see how this works, but
'ship' could be 'ss' (prefix in ship names eg SS Great Britain) and 'ss' is located in the answer.
an anagram of 'seas' is 'aess' which is within the left over letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for assess that I've seen before include "Estimate, gauge" , "Estimate the worth or quality of" , "Remedy for all ills" , "Evaluate, estimate" , "Fix the amount of tax" .)