Touch number read as Arabic in church monument (8)
I believe the answer is:
Here is my best explanation:
'monument' is the definition.
(cenotaph is a kind of monument)
'touch number read as arabic in church' is the wordplay.
'touch' becomes 'pat' (pat is a kind of touch).
'number' becomes 'one' (one is a kind of number).
'read as arabic' says the letters should be written backwards (Arabic is read from right to left).
'in' indicates putting letters inside.
'church' becomes 'ch' (common abbreviation).
'patone' reversed gives 'enotap'.
'enotap' placed into 'ch' is 'CENOTAPH'.
(Other definitions for cenotaph that I've seen before include "Monument honouring the fallen", "Tomb", "Empty tomb", "Memorial", "Monument to those killed in war", "War memorial", "Feature of Whitehall", "Monument built to honour soldiers who died in war", "feature" and "construction in Whitehall".)