Delectable little stone in a river (5)
I believe the answer is:
tasty
'delectable' is the definition.
(I've seen this in another clue)
'little stone in a river' is the wordplay.
'little stone' becomes 'st' (abbreviation. I am not sure about the 'little' bit.).
'in' means one lot of letters goes inside another.
'a river' becomes 'tay' (Scottish river).
'st' put within 'tay' is 'TASTY'.
Can you help me to learn more?
(Other definitions for tasty that I've seen before include "Sexually attractive?" , "Appetising, having pleasant flavour" , "Pleasantly flavoursome" , "Having good flavour" , "Mouth-watering" .)