The great man shows some sagacity (3)
I believe the answer is:
aga
'the great man' is the definition.
The definition suggests a singular noun which matches the answer.
'some sagacity' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'AGA' is hidden within 'sagacity'.
'shows' is the link.
Can you help me to learn more?
(Other definitions for aga that I've seen before include "of the 17 [KITCHEN]" , "Muslim title and cooking stove" , "- Khan, Ismaili leader" , "Eastern leader" , "Oven" .)