Coloured container with painful tentacles (10)
I believe the answer is:
bluebottle
'with painful tentacles' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'coloured container' is the wordplay.
'coloured' becomes 'blue' (similar in meaning).
'container' becomes 'bottle' (bottle is a kind of container).
'blue'+'bottle'='BLUEBOTTLE'
Can you help me to learn more?
(Other definitions for bluebottle that I've seen before include "Officer" , "Flier" , "Copper - fly" , "get a buzz out of it!" , "An insect; Goon character" .)