Preferably cheer at heroic part (6)
I believe the answer is:
rather
'preferably' is the definition.
(I know that preferably can be written as rather)
'cheer at heroic part' is the wordplay.
'part' indicates the answer is hidden within the clue.
'RATHER' is hidden in the letters of 'cheer at heroic'.
(Other definitions for rather that I've seen before include "Fairly" , "Somewhat; more willingly" , "To a limited degree" , "Most certainly" , "More willingly, by preference" .)