Identical kindergarten with fish glittering (9)
I believe the answer is:
twinkling
'glittering' is the definition.
(thesaurus)
'identical kindergarten with fish' is the wordplay.
'identical kindergarten' becomes 'twink' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'with' says to put letters next to each other.
'fish' becomes 'ling' (ling is a kind of fish).
'twink'+'ling'='TWINKLING'
Can you help me to learn more?
(Other definitions for twinkling that I've seen before include "Sparkling like a star" , "Shining intermittently" , "Sparkling - moment" , "Instant" , "How stars appear" .)