Tardy and slow getting into bed (7)
I believe the answer is:
belated
'tardy' is the definition.
(synonyms)
'slow getting into bed' is the wordplay.
'slow' becomes 'late' (I've seen this in another clue).
'getting into' is an insertion indicator.
'late' going inside 'bed' is 'BELATED'.
'and' acts as a link.
(Other definitions for belated that I've seen before include "Bleated, being overdue" , "Tardy" , "delayed" , "Coming too late" , "Out of date" .)