Slightly depressed to see discontented republicans secede, ill-advisedly (8)
I believe the answer is:
recessed
'republicans secede ill-advisedly' is the definition.
I can't judge whether this defines the answer.
'slightly depressed to see discontented' is the wordplay.
'slightly depressed' becomes 'cessed' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'to' says to put letters next to each other (I've seen this in other clues).
'see' becomes 'rome' (the Holy See or See of Rome is home to the pope).
'discontented' means to remove the middle letters (the word's contents are removed).
'rome' with its centre removed is 're'.
'cessed' put after 're' is 'RECESSED'.
Can you help me to learn more?
(Other definitions for recessed that I've seen before include "along the lines of bay" , "Set back by seceders" , "Adjourned or suspended" , "Set back in at wall" .)