So-called smart creature - it tells the time to kids in the garden! (9)
I believe the answer is:
dandelion
'it tells the time to kids in the garden' is the definition.
The definition suggests a singular noun which matches the answer.
'so-called smart creature' is the wordplay.
'so called smart' becomes 'dande' (I can't justify this - if you can you should give a lot more credence to this answer).
'creature' becomes 'lion' (I've seen this before).
'dande'+'lion'='DANDELION'
Can you help me to learn more?
(Other definitions for dandelion that I've seen before include "Wild plant with "clock"" , "Common yellow-flowered weed" , "Wild flower with serrated leaves" , "One blooming" , "Yellow weed" .)