One's turn done with no restraints in cell (6)
I believe the answer is:
neuron
'cell' is the definition.
(neuron is a kind of cell)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for neuron that I've seen before include "Impulsive thing" , "Nerve impulse cell" , "Conductor" , "Part of one's nervous system" , "Transmitter of nerve impulses" .)