A dear item in the mason's yard (5)
I believe the answer is:
brick
'a dear item' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'mason's yard' is the wordplay.
'mason's' becomes 'bric' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'yard' becomes 'K' (synonyms).
'bric'+'k'='BRICK'
'in the' acts as a link.
Can you help me to learn more?
(Other definitions for brick that I've seen before include "Clay building block" , "dropped?" , "Building unit?" , "Baked clay" , "Jolly good fellow!" .)