On paper, an assurance of accuracy (3)
I believe the answer is:
sic
'on paper an assurance of accuracy' is the definition.
I can't tell whether this defines the answer.
'on paper an assurance of accuracy' is the wordplay.
'on' means one lot of letters goes inside another (as in clothing 'on' a person).
'paper' becomes 'i' (the i is a UK newspaper).
'an assurance of accuracy' becomes 'sc' (I can't explain this - if you can you should believe this answer much more).
'i' inserted within 'sc' is 'SIC'.
Can you help me to learn more?
(Other definitions for sic that I've seen before include "poorly spelt if requiring this" , "the reading is correct" , "Thus in classical way" , "Printing term to denote accuracy though it appears otherwise" , "It calls attention to a quoted mistake" .)