Muck, perhaps dissolves evenly? (4)

I believe the answer is:
isle
'muck' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'dissolves evenly?' is the wordplay.
'evenly?' means one should take alternating letters (the letters in even-numbered positions).
The alternating letters of 'dissolves' are 'ISLE'.
'perhaps' is the link.
Can you help me to learn more?
(Other definitions for isle that I've seen before include "It lies badly in water" , "Fair ---, knitting style" , "Lies (anag)" , "Man, possibly" , "Dogs, maybe" .)
