A planet's teribly nice (8)
I believe the answer is:
pleasant
'nice' is the definition.
(similar in meaning)
'a planet's teribly' is the wordplay.
'a planet's' can be anagrammed to 'PLEASANT'.
However, I am unsure how the anagram is indicated.
Can you help me to learn more?
(Other definitions for pleasant that I've seen before include "Satisfying, likeable" , "Nice, satisfying" , "Enjoyable, nice" , "Attractive" , "sweet?" .)