Blue pole with notice attached (3)
I believe the answer is:
sad
'blue' is the definition.
(I know that blue can be written as sad)
'pole with notice attached' is the wordplay.
'pole with' becomes 's' (abbreviation for South, as in South Pole. I am not sure about the 'with' bit.).
'notice' becomes 'ad' (both can mean an advertisement).
'attached' means one lot of letters go next to another.
's'+'ad'='SAD'
Can you help me to learn more?
(Other definitions for sad that I've seen before include "Mournful and depressed" , "Blue" , "Miserable" , "Despondent" , "Mournful - sorry" .)