Precipitates things, giving Kitty instructions for shopping by the sound of it (8)
I believe the answer is:
catalyst
'precipitates things' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'kitty instructions for shopping by the sound of it' is the wordplay.
I cannot quite see how this works, but
'kitty' could be 'cat' and 'cat' is located in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'giving' acts as a link.
Can you help me to learn more?
(Other definitions for catalyst that I've seen before include "accelerator" , "Agent promoting change" , "Thing that causes a change" , "It causes something to happen, in chemistry say" , "It causes chemical change" .)