A quarter hour in bed, perhaps, can make you late! (6)
I believe the answer is:
behind
'late' is the definition.
(thesaurus)
'a quarter hour in bed' is the wordplay.
'a quarter hour' becomes 'hin' (I can't explain this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'hin' going within 'bed' is 'BEHIND'.
'perhaps can make you' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for behind that I've seen before include "Following - trailing - supporting" , "Rear - losing" , "In arrears; guiding" , "bum" , "Hidden by; in arrears" .)