In-depth disheartened author's novel means of putting characters on paper (9)

'means of putting characters on paper' is the definition.
(a printhead prints characters on paper)

'in-depth disheartened author's novel' is the wordplay.
'disheartened' says to hollow out the word (remove centre letters) (the middle or heart is removed).
'novel' indicates an anagram (letters in a new or novel order).
'author' with its centre taken out is 'ar'.
'in'+'depth'+'ar'='indepthar'
'indepthar' anagrammed gives 'PRINTHEAD'.