During passage, nothing lost from recycling change of key (2,7)
I believe the answer is:
in transit
'nothing lost from recycling change of key' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'during passage' is the wordplay.
'during' becomes 'in' (e.g. during February means in February).
'passage' becomes 'transit' (synonyms).
'in'+'transit'='IN TRANSIT'
Can you help me to learn more?
(Other definitions for in transit that I've seen before include "Being transported" , "On its way" , "on the move?" , "En route" , "While being conveyed" .)