Lobster atop coloured stick (6)
I believe the answer is:
crayon
'coloured stick' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'lobster atop' is the wordplay.
'lobster' becomes 'cray' (I can't explain this - if you can you should believe this answer much more).
'atop' becomes 'on'.
'cray'+'on'='CRAYON'
Can you help me to learn more?
(Other definitions for crayon that I've seen before include "alternative to charcoal" , "Coloured wax pencil" , "Drawing-stick" , "Pencil of chalk or wax" , "Drawing pen" .)