As a leader of men, nothing less than cool (3)
I believe the answer is:
col
'as a leader of men nothing' is the definition.
I can't tell whether this defines the answer.
'less than cool' is the wordplay.
'less than' means to remove the last letter (not the full word).
'cool' becomes 'cold' (associated in meaning).
'cold' with its final letter taken off is 'COL'.
Can you help me to learn more?
(Other definitions for col that I've seen before include "Lowest point of ridge between two peaks" , "Low point of a ridge" , "Mountain defile" , "A pass through ridge" , "Low area between peaks" .)