He wrote line about good companion (10)
I believe the answer is:
longfellow
'he wrote' is the definition.
(US poet Henry Wadsworth Longfellow)
'line about good companion' is the wordplay.
'line about' becomes 'lon' (I am not sure about this - if you are sure you should believe this answer much more).
'good' becomes 'g' (abbreviation).
'companion' becomes 'fellow' (synonyms).
'lon'+'g'+'fellow'='LONGFELLOW'
Can you help me to learn more?
(Other definitions for longfellow that I've seen before include "Song of_Hiawatha poet" , "American poet, author of 17" , "Hiawatha poet" .)