Hesitation after almost last final demand (9)
I believe the answer is:
ultimatum
'demand' is the definition.
(I know that ultimatum is a type of demand)
'hesitation after almost last final' is the wordplay.
'hesitation' becomes 'um' (um is said in hesitation).
'after' means one lot of letters go next to another.
'almost' becomes 'ultima' (I can't justify this - if you can you should give a lot more credence to this answer).
'final' indicates one should take the final letters.
The last letter of 'last' is 't'.
'ultima'+'t'='ultimat'
'um' after 'ultimat' is 'ULTIMATUM'.
Can you help me to learn more?
(Other definitions for ultimatum that I've seen before include "A final demand - or else" , "Final offer" , "Threat" , "Final proposition or demand" , "Final point" .)