Damage marrow, destroying half (3)

I believe the answer is:

mar

'damage' is the definition.
(marring is a kind of damaging)

'marrow destroying half' is the wordplay.
'destroying half' indicates taking half.
'marrow' halved is 'MAR'.

(Other definitions for mar that I've seen before include "Ram into and spoil" , "wreck" , "'Damage, impair (3)'" , "Blemish" , "when spring growth starts?" .)

I've seen this clue in The Times.

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