Stick around a little, because this is sweet (7)
I believe the answer is:
glucose
'this is sweet' is the definition.
(type of sugar)
'stick around a little because' is the wordplay.
'stick' becomes 'glue' (to stick with glue).
'around' means one lot of letters goes inside another.
'a little because' becomes 'cos' (short for 'because').
'glue' going around 'cos' is 'GLUCOSE'.
(Other definitions for glucose that I've seen before include "Sweet substance" , "Form of sugar found in fruit etc" , "Naturally occurring sugar" , "syrupy stuff" , "An important source of body energy" .)