I left Arctic nomad circling polar cap, say (5)
I believe the answer is:
input
'say' is the definition.
(I've seen this in another clue)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for input that I've seen before include "Signal supplied to a device" , "Data entry" , "Contribution of work or information" , "data-feed" , "Feed data into a computer" .)