Dead on time? No (4)
I believe the answer is:
late
'dead' is the definition.
(similar in meaning)
'on time? no' is the wordplay.
'on' indicates putting letters inside (as in clothing 'on' a person).
'time?' becomes 't' (abbreviation).
'no' becomes 'lae' (I can't explain this - if you can you should believe this answer much more).
't' placed into 'lae' is 'LATE'.
Can you help me to learn more?
(Other definitions for late that I've seen before include "Running behind time" , "Previous" , "Not yet arrived - departed" , "Recently dead" , "In arrears" .)