Falling on a stool (8)
I believe the answer is:
dropping
'falling on a stool' is the definition.
'dropping' can be an answer for 'falling' (I've seen this before). I am unsure of the 'on a stool' bit.
'falling on a stool' is the wordplay.
'falling' becomes 'drop' (synonyms).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'a stool' becomes 'ping' (I can't explain this - if you can you should believe this answer much more).
'drop'+'ping'='DROPPING'
Can you help me to learn more?
(Other definitions for dropping that I've seen before include "''For peace comes ... slow'' (W B Yeats)" , "Falling" , "Letting fall" .)