Flipping work! Drudge penning book, which should pay the bills (9)
I believe the answer is:
potboiler
'should pay the bills' is the definition.
I can't judge whether this definition defines the answer.
'flipping work drudge penning book' is the wordplay.
'flipping' shows that the letters should be reversed in order.
'work' becomes 'op' (abbreviation for opus).
'drudge' becomes 'toiler' (I've seen this in another clue).
'penning' means one lot of letters goes inside another.
'book' becomes 'b' (abbreviation for book).
'op' written backwards gives 'po'.
'toiler' enclosing 'b' is 'tboiler'.
'po'+'tboiler'='POTBOILER'
'which' acts as a link.
Can you help me to learn more?
(Other definitions for potboiler that I've seen before include "Inferior art or literary work produced chiefly for money" , "likely to be steamy?" , "popular item" , "Money-making book" , "Literary work of poor quality" .)