Last prisoner can use no shilling (8)
I believe the answer is:
continue
'last' is the definition.
(I've seen this before)
'prisoner can use no shilling' is the wordplay.
'prisoner' becomes 'con' (abbreviation for 'convict').
'can' becomes 'tin' (both are metal containers).
'no' indicates named letters should be taken away.
'shilling' becomes 's' (abbreviation e.g. Lsd - pounds, shillings, pence).
'use' with 's' taken away is 'ue'.
'con'+'tin'+'ue'='CONTINUE'
(Other definitions for continue that I've seen before include "Last" , "Go on without stopping" , "Carry on" , "Proceed" , "Persist" .)