Showing shrewdness, mean to enmesh the copper in (6)
I believe the answer is:
acumen
'showing shrewdness' is the definition.
'acumen' can be an answer for 'shrewdness' (acumen can mean shrewdness or good judgment). I'm not certain of the 'showing' bit.
'mean to enmesh the copper in' is the wordplay.
I cannot quite see how this works, but
'copper' could be 'cu' (Cu is the chemical symbol for copper) and 'cu' is present in the answer.
an anagram of 'mean' is 'amen' which is present in the remaining 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 acumen that I've seen before include "intuition" , "show perception" , "Sagicity as in business" , "brightness" , "Shrewdness, good for business" .)