A column of people (8)
I believe the answer is:
backbone
'a column of people' is the definition.
(spinal column)
'a column' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'one' and 'one' is present in the answer.
This explanation may well be incorrect...
(Other definitions for backbone that I've seen before include "Spine or courage" , "Firmness of character" , "Informal courage of spinal kind" , "Spinal column courage" , "Steel" .)