Started with pastry (4)
I believe the answer is:
tart
'pastry' is the definition.
(type of pastry)
'started with' is the wordplay.
'with' indicates a hidden word.
'TART' can be found hidden inside 'started'.
(Other definitions for tart that I've seen before include "Bitter - sweet - floozie" , "Open cake with jam etc" , "sour type of pie" , "Of taste, sharp or acid" , "quiche, perhaps" .)