Pillar just made centrepiece of cell (5)
I believe the answer is:
newel
'pillar' is the definition.
(I know that newel is a type of pillar)
'just made centrepiece of cell' is the wordplay.
'just made' becomes 'new' (I've seen this in another clue).
'centrepiece of' says to take the centre (piece from the middle).
The central letters of 'cell' are 'el'.
'new'+'el'='NEWEL'
(Other definitions for newel that I've seen before include "End post on stair rail" , "Post of winding stairs" , "Support post for stair rail" , "Post supporting stair rail" , "domestic post" .)