Pay cut with last of cheques in post, frantic (2,4,4,3)
I believe the answer is:
at ones wits end
'frantic' is the definition.
'pay cut with last of cheques in post' is the wordplay.
'pay' becomes 'atone' (I've seen this before).
'cut with last of cheques' becomes 'wits' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'post' becomes 'send' (synonyms).
'wits' placed inside 'send' is 'switsend'.
'atone'+'switsend'='AT ONES WITS END'
Can you help me to learn more?
(Other definitions for at ones wits end that I've seen before include "Unable to see a way forward when in trouble" , "Desperate" , "Not knowing what to do next" , "In a state of desperation" , "at a loss" .)