Two names I later falsified, under cover? (8)
I believe the answer is:
internal
'under cover?' is the definition.
'two names i later falsified' is the wordplay.
'two names' means two substitutions for 'name'.
'name' becomes 'n' (common abbreviation e.g. on forms).
'name' becomes 'n' (common abbreviation e.g. on forms).
'falsified' indicates an anagram.
'n'+'n'+'i'+'later'='nnilater'
'nnilater' with letters rearranged gives 'INTERNAL'.
(Other definitions for internal that I've seen before include "Located inside" , "Within the body" , "Domestic" , "In-house - private" , "Inside the body" .)