Sweet shop robbed as regulars left on time (6)
I believe the answer is:
sorbet
'sweet' is the definition.
(sorbet is a kind of sweet)
'regulars left on time' is the wordplay.
'regulars' indicates alternate letters (letters selected at regular intervals).
'on' means one lot of letters go next to another.
'time' becomes 'sorb' (I can't justify this - if you can you should give a lot more credence to this answer).
The alternate letters of 'left' are 'et'.
'et' after 'sorb' is 'SORBET'.
'shop robbed as' is the 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 sorbet that I've seen before include "Granita-like dessert" , "Fruit juice and water ice" , "Water ice to cleanse the palate" , "Sherbet, water-ice" , "Refresher course" .)