Polish picture that depicts decisive crossing (7)
I believe the answer is:
rubicon
'polish picture that depicts decisive crossing' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'polish picture' is the wordplay.
'polish' becomes 'rub' (polish meaning rub to make shiny).
'picture' becomes 'icon' (synonyms).
'rub'+'icon'='RUBICON'
Can you help me to learn more?
(Other definitions for rubicon that I've seen before include "Stream in north Italy that Julius Caesar crossed in 49 BC" , "win at piquet" , "term used in 12 [PIQUET]" , "Caeser crossed this river in a decisive step- no going back" , "Line fatefully gone over" .)