A hard-back (5)

I believe the answer is:

stern

I believe this clue is a double definition.

'a hard' is the first definition.
(thesaurus)

'back' is the second definition.
(stern is a kind of back)

(Other definitions for stern that I've seen before include "Grim; severe" , "Rear; severe, serious" , "Tail of a beagle" , "Strict - forbidding" , "Severe, demanding" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.