Find a description of each other planet? (7)
I believe the answer is:
unearth
'find a description' is the definition.
'unearth' can be an answer for 'find' (unearthing is a kind of finding). I'm not sure about the 'a description' bit.
'each other planet?' is the wordplay.
'each other' becomes 'un' (I can't explain this - if you can you should believe this answer much more).
'planet?' becomes 'earth' (Earth is an example).
'un'+'earth'='UNEARTH'
'of' acts as a link.
(Other definitions for unearth that I've seen before include "Bring to light, excavate" , "Bring out of obscurity" , "Exhume" , "Dig up for a hunter" , "Dig up or find for haunter" .)