Book senior hack and trendy medic into golf club (5,5)
I believe the answer is:
edwin drood
'book' is the definition.
(Charles Dickens' The Mystery of Edwin Drood)
'senior hack and trendy medic into golf club' is the wordplay.
'senior hack' becomes 'ed' (short for editor - hack can mean journalist).
'and' says to put letters next to each other.
'trendy medic' becomes 'indr' (I can't justify this - if you can you should give a lot more credence to this answer).
'into' indicates putting letters inside.
'golf club' becomes 'wood' (I've seen this before).
'indr' placed into 'wood' is 'windrood'.
'ed'+'windrood'='EDWIN DROOD'
(Other definitions for edwin drood that I've seen before include "Dickensian character" , "Dickens's unfinished mystery tale" , "7 27 [CHARLES DICKENS] hero" , "man of mystery" , "The Mystery of -- -- (Dickens; unfinished)" .)