The sort of sea to suit a cutter? (6)
I believe the answer is:
choppy
I'm afraid I can't explain this answer.
Can you help me to learn more?
(Other definitions for choppy that I've seen before include "Somewhat rough (sea)" , "Moderately rough (sea)" , "Slightly rough (at sea)" , "(Of seas) rough" , "(Of sea) with many small waves" .)