He painted beings, terrestrial and otherwise (5)
I believe the answer is:
manet
'terrestrial and otherwise' is the definition.
I can't judge whether this definition defines the answer.
'he painted beings' is the wordplay.
'he' becomes 'man'.
'painted beings' becomes 'et' (I can't justify this - if you can you should give a lot more credence to this answer).
'man'+'et'='MANET'
Can you help me to learn more?
(Other definitions for manet that I've seen before include "Olympia painter" , "Olympia artist" , "Edouard ___, painted Dejeuner sur l'herbe, d. 1883" , "French painter" , "Edouard -- (artist)" .)