Song that meant he must take part (6)
I believe the answer is:
anthem
'song' is the definition.
(anthem is a kind of song)
'meant he must take part' is the wordplay.
'take part' indicates a hidden word (I've seen 'taking part' mean this).
'ANTHEM' is hidden in the letters of 'meant he must'.
'that' is the link.
(Other definitions for anthem that I've seen before include "National tune" , "Song in praise of a nation" , "Church choral piece" , "The man for a patriotic song" , "The man for a rousing song" .)