Rower or butterfly, say (6)
I believe the answer is:
stroke
I believe this is a double definition.
'rower' is the first definition.
(term for a rower)
'butterfly say' is the second definition.
(butterfly is a kind of stroke)
'or' is the link.
(Other definitions for stroke that I've seen before include "Attack of apoplexy" , "butterfly?" , "Mark made by brush" , "Brain haemorrhage or caress" , "A blow or brain seizure" .)