Steed around start of Avengers getting rough (6)
I believe the answer is:
hoarse
'rough' is the definition.
(thesaurus)
'steed around start of avengers' is the wordplay.
'steed' becomes 'horse' (I've seen this before).
'around' indicates putting letters inside.
'start of' indicates taking the first letters.
The first letter of 'avengers' is 'a'.
'horse' placed around 'a' is 'HOARSE'.
'getting' is the link.
(Other definitions for hoarse that I've seen before include "With a rough husky voiced" , "Of voice, rough and dry" , "Ashore (anag)" , "Of voice, sounding rough" , "(Of voice) rough, harsh" .)