Account receives peer review, initially a tough task (4,5)
I believe the answer is:
tall order
'a tough task' is the definition.
(a tall order is a difficult task)
'account receives peer review initially' is the wordplay.
'account' becomes 'tale' (tale is a kind of account).
'receives' indicates putting letters inside (inserted letters are received).
'peer' becomes 'lord' (lord is a type of peer).
'review initially' becomes 'r' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'tale' enclosing 'lord' is 'tallorde'.
'tallorde'+'r'='TALL ORDER'
Can you help me to learn more?
(Other definitions for tall order that I've seen before include "Formidable task" , "Unreasonable demand" , "I want a skyscraper built by tomorrow" , "delivery of sequoias?" , "Request to tax" .)