Cry from main cavalcade essentially surrounding queen (6)
I believe the answer is:
squeal
'cry' is the definition.
(thesaurus)
'main cavalcade essentially surrounding queen' is the wordplay.
'main' becomes 'sea' (the main is an old name for the sea).
'essentially' means to look at the middle letters.
'surrounding' is an insertion indicator.
'queen' becomes 'qu' (abbreviation for queen).
The centre of 'cavalcade' is 'l'.
'sea'+'l'='seal'
'seal' enclosing 'qu' is 'SQUEAL'.
'from' acts as a link.
(Other definitions for squeal that I've seen before include "Inform on someone" , "Sing" , "Equals (anag)" , "Study of plants" , "Squeak; inform" .)