Compares elk, in this, finally roaming (6)
I believe the answer is:
likens
'compares' is the definition.
('liken' can be a synonym of 'compare')
'elk in this finally roaming' is the wordplay.
'finally' indicates one should take the final letters.
'roaming' indicates anagramming the letters.
The last letter of 'this' is 's'.
'elk'+'in'+'s'='elkins'
'elkins' is an anagram of 'LIKENS'.
(Other definitions for likens that I've seen before include "Points out the resemblance of one thing to another" , "Compares" .)