Not the same on earth, strangely (7)
I believe the answer is:
another
'not the same' is the definition.
(I've seen this before)
'on earth strangely' is the wordplay.
'strangely' indicates anagramming the letters.
'on'+'earth'='onearth'
'onearth' is an anagram of 'ANOTHER'.
(Other definitions for another that I've seen before include "No heart (anag.)" , "Someone else" , "Somebody else" , "Additional, one more" , "A further (item)" .)