Mark of wound allowed to be red (7)
I believe the answer is:
scarlet
'be red' is the definition.
(I've seen this before)
'mark of wound allowed' is the wordplay.
'mark of wound' becomes 'scar' (I've seen this before).
'allowed' becomes 'let' (I've seen this before).
'scar'+'let'='SCARLET'
'to' is the link.
(Other definitions for scarlet that I've seen before include "Crimson" , "Clarets (anag.)" , "Fallen" , "Colour of embarrassment?" , "immoral" .)