Cancel a berth out of complete freedom (5,7)
I believe the answer is:
carte blanche
'complete freedom' is the definition.
(I've seen this before)
'cancel a berth out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'cancel'+'a'+'berth'='cancelaberth'
'cancelaberth' with letters rearranged gives 'CARTE-BLANCHE'.
'of' acts as a link.
(Other definitions for carte blanche that I've seen before include "Full discretionary power" , "free rein" , "Complete discretion" , "Complete freedom to act as one wishes" , "Complete freedom of action" .)