Reportedly an island crew (5)
I believe the answer is:
eight
'crew' is the definition.
(an eight-person rowing team)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for eight that I've seen before include "Number (with pieces?)" , "Mathematical cube" , "team rowing" , "Set of rowers" , "Oxygen's atomic number" .)