Keep back intelligence two hours out of date (8)
I believe the answer is:
withhold
'keep back' is the definition.
(synonyms)
'intelligence two hours out of date' is the wordplay.
'intelligence' becomes 'wit' (wit is a kind of intelligence).
'two' shows that letters should be duplicated.
'hours' becomes 'h'.
'out of date' becomes 'old' (I've seen this in another clue).
'h' duplicated is 'hh'.
'wit'+'hh'+'old'='WITHHOLD'
(Other definitions for withhold that I've seen before include "Keep in reserve, do not release" , "restrain" , "Refrain from revealing" , "Refuse to give or grant" , "Keep back" .)