Banter, as such, going over head of inmate, fellow prisoner (10)
I believe the answer is:
persiflage
'banter' is the definition.
(persiflage is a kind of banter)
'as such going over head of inmate fellow prisoner' is the wordplay.
'as such' becomes 'perse' ('per se' can be a synonym of 'as such').
'going over' indicates putting letters inside.
'head of' indicates taking the first letters.
'prisoner' becomes 'lag' (I've seen this before).
The initial letters of 'inmate fellow' is 'if'.
'if'+'lag'='iflag'
'perse' placed around 'iflag' is 'PERSIFLAGE'.
(Other definitions for persiflage that I've seen before include "Pale griefs (anag) - flippancy" , "Railing" , "Badinage, banter" , "Rallying" , "Light mockery, banter" .)