Go over boundary of reasonable limit (5)
I believe the answer is:
recap
'go over' is the definition.
(I've seen this before)
'boundary of reasonable limit' is the wordplay.
'boundary of' suggests removing the centre (I've seen 'boundaries of' mean this).
'limit' becomes 'cap' (capping is a kind of limiting).
'reasonable' with its middle taken out is 're'.
're'+'cap'='RECAP'
(Other definitions for recap that I've seen before include "Summarise (colloq.)" , "Retrospective summary" , "Go over the main points again, in short" , "Restate" , "Caper (anag)" .)