Baltic supplier seen in moderation (4)
I believe the answer is:
oder
'baltic supplier' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'in moderation' is the wordplay.
'in' says the answer is hidden in the clue.
'ODER' can be found hidden inside 'moderation'.
'seen' is the link.
Can you help me to learn more?
(Other definitions for oder that I've seen before include "European flower" , "East European river" , "Rode around the European river" , "School blazer insignia" , "River that, with the Neisse, forms the German-Polish border" .)