Flake found in case of Slavic beer (5)
I believe the answer is:
scale
'flake' is the definition.
(thesaurus)
'case of slavic beer' is the wordplay.
'case of' means to remove the middle letters (outsides of).
'beer' becomes 'ale' (I've seen this before).
'slavic' with its middle taken out is 'sc'.
'sc'+'ale'='SCALE'
'found in' acts as a link.
(Other definitions for scale that I've seen before include "Series of notes in an octave" , "Size ratio; skin flake" , "Tones rising maybe" , "range" , "Relative extent as of laces" .)