A steel product with prickles (6)
I believe the answer is:
teasel
'with prickles' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'a steel product' is the wordplay.
'a steel' anagrams to 'TEASEL'.
But, I am not clear how this is indicated.
Can you help me to learn more?
(Other definitions for teasel that I've seen before include "Spiny flower head" , "Sat Lee down on the spiny herb" , "Sat eel up on the herb" , "Plant with spiny purple flower heads" , "Plant with prickly flower head" .)