Mark of an oarsman (6)
I believe the answer is:
stroke
I believe this is a double definition.
'mark' is the first definition.
(I know that stroke is a type of punctuation)
'an oarsman' is the second definition.
(I know that stroke is a type of oarsman)
'of' is the link.
(Other definitions for stroke that I've seen before include "Brain haemorrhage or caress" , "Medical seizure - effect of sun - oarsman" , "Caress; batsman's hit" , "Blow - gentle touch - brain damage" , "Drive" .)