At one's wits' end, shed tears when brushed off (5)
I believe the answer is:
swept
'brushed off' is the definition.
'swept' can be an answer for 'brushed' ('sweep' can be a synonym of 'brush'). I am not sure about the 'off' bit.
'at one's wits' end shed tears' is the wordplay.
'at one's wits' end' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'shed tears' becomes 'wept' (I've seen this in another clue).
's'+'wept'='SWEPT'
'when' is the link.
Can you help me to learn more?
(Other definitions for swept that I've seen before include "Cleaned by broom" , "overwhelmed" , "Quickly passed" , "Was searcher" , "passed proudly" .)