Resting place for fish (5)
This clue is a double definition.
'resting place' is the first definition.
(I've seen this before)
'fish' is the second definition.
(I know that perch is a type of fish)
'for' acts as a link.
(Other definitions for perch that I've seen before include "Freshwater fish - roost" , "Fish; pole" , "Bird's roost" , "Bird's resting place or old measure of length" , "Resting place for a bird and old measure" .)
'fish' is the definition.
(I know that Perca is a type of fish)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Another definition for perca that I've seen is " genus of fishes".)