Huge Elgar composition (5)
I believe the answer is:
large
'huge' is the definition.
(similar in meaning)
'elgar composition' is the wordplay.
'composition' indicates anagramming the letters (letters arranged or composed in a different order).
'elgar' is an anagram of 'LARGE'.
(Other definitions for large that I've seen before include "Little's late partner" , "Immense" , "Titanic" , "Strapping" , "Lager (anag.)" .)