Last of Highland drink in glen (4)
I believe the answer is:
dale
'glen' is the definition.
(thesaurus)
'last of highland drink' is the wordplay.
'last of' suggests the final letters.
'drink' becomes 'ale' (ale is a kind of drink**).
The final letter of 'highland' is 'd'.
'd'+'ale'='DALE'
'in' acts as a link.
(Other definitions for dale that I've seen before include "Valley; man's name" , "An English valley" , "See 8" , "Low ground" , "Valley; Trollope's Bell and Lily" .)