Sweetheart takes a little time on holiday (9)
I believe the answer is:
honeymoon
'holiday' is the definition.
(I know that honeymoon is a type of holiday)
'sweetheart takes a little time on' is the wordplay.
'sweetheart' becomes 'honey' (I've seen this in another clue).
'takes' is a charade indicator (letters next to each other).
'a little time' becomes 'mo' (a 'mo' is a short amount of time).
'honey'+'mo'+'on'='HONEYMOON'
(Other definitions for honeymoon that I've seen before include "Introductory period" , "Sequel to marriage" , "romantic break" , "Holiday following wedding" , "Post-nuptial holiday" .)