The man composed a song (6)
I believe the answer is:
anthem
'a song' is the definition.
(anthem is a kind of song)
'the man composed' is the wordplay.
'composed' indicates an anagram.
'the'+'man'='theman'
'theman' anagrammed gives 'ANTHEM'.
(Other definitions for anthem that I've seen before include "air of patriotism?" , "The man for a patriotic song" , "National or church song" , "The man for a popular song" , "Solemn song" .)