The sagacity of having a department at each end (5)
I believe the answer is:
depth
'the sagacity' is the definition.
(thesaurus)
'department at each end' is the wordplay.
'department' becomes 'dept'.
'at' says to put letters next to each other.
'end' says to take the final letters.
The final letter of 'each' is 'h'.
'dept'+'h'='DEPTH'
'of having a' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for depth that I've seen before include "Distance downwards" , "Downward extent" , "Thoroughness" , "Distance from top down as in water" , "Military life; vulgarly artificial" .)