One spot on about force of old religious image (8)
I believe the answer is:
crucifix
'religious image' is the definition.
'one spot on about force of old' is the wordplay.
'one' becomes 'i' (Roman numeral).
'spot' becomes 'fix' (both can mean a difficult or tricky situation).
'on' is a charade indicator (letters next to each other).
'about' becomes 'c' (abbreviation for 'circa').
'force of old' becomes 'ruc' (Royal Ulster Constabulary, old police force).
'i'+'fix'='ifix'
'c'+'ruc'='cruc'
'ifix' put after 'cruc' is 'CRUCIFIX'.
(Other definitions for crucifix that I've seen before include "Necklace popular with Christians" , "Representation of the cross on which Jesus died" , "The Christian cross" , "Religious cross" , "Christian symbol" .)