Zero room in entire trans-dimensional passage (8)
I believe the answer is:
wormhole
'trans-dimensional passage' is the definition.
I can't judge whether this defines the answer.
'zero room in entire' is the wordplay.
'zero' becomes 'O' (O resembles 0).
'room' becomes 'rm' (abbreviation for room).
'in' indicates putting letters inside.
'entire' becomes 'whole' (similar in meaning).
'o'+'rm'='orm'
'orm' put within 'whole' is 'WORMHOLE'.
Can you help me to learn more?
(Other definitions for wormhole that I've seen before include "Hypothetical link across space-time" , "In theory, shortcut in space" , "Space made by burrowing creatures in fruit, wood, books etc" , "Hypothetical tunnel in space-time" , "Cavity make in wood by burrowing larvae" .)