Austere box belt (7)

I believe the answer is:

spartan

'austere' is the definition.
(I know that austere can be written as spartan)

'box belt' is the wordplay.
'box' becomes 'spar' (spar can mean to box).
'belt' becomes 'tan' (both can mean to hit).
'spar'+'tan'='SPARTAN'

(Other definitions for spartan that I've seen before include "Basic" , "toughly-disciplined type" , "austere old Greek" , "Strictly disciplined" , "Austere - like Lysander?" .)

I've seen this clue in The Guardian.

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