Alternatively have a paddle (3)
I believe the answer is:
Here is my best explanation:
'paddle' is the definition.
(I've seen this before)
'alternatively have a' is the subsidiary indication.
'alternatively' becomes 'or'.
'have' is an insertion indicator.
'or' placed around 'a' is 'oar'.
(Other definitions for oar that I've seen before include "Sportsman", "Paddle", "Rower's paddle", "Rowing blade", "A manual boat propeller", "Use it to move a boat", "Boat propellant", "One of an eight", "propellor" and "Implement to propel a boat".)