Mark drinks audibly (6)
I believe the answer is:
bruise
'mark' is the definition.
(I have seen 'Mark of blow ' mean 'bruise' so perhaps 'mark' could also mean 'bruise')
'drinks audibly' is the wordplay.
'drinks' becomes 'brews' (brew is a kind of drink).
'audibly' indicates a 'sounds like' (homophone) clue.
'brews' is a homophone of 'BRUISE'.
(Other definitions for bruise that I've seen before include "Mark left by blow" , "Contusion" , "Skin injury" , "Superficial injury" , "Injure underlying soft tissue or bone" .)