Sovereign leads company support for a snake (4,5)
I believe the answer is:
king cobra
'a snake' is the definition.
(king cobra is a kind of snake)
'sovereign leads company support' is the wordplay.
'sovereign' becomes 'king' (king is a kind of sovereign).
'leads' means one lot of letters go next to another.
'company' becomes 'co' (abbreviation).
'support' becomes 'bra' (a support for the breasts).
'king'+'co'+'bra'='KING COBRA'
'for' acts as a link.
(Other definitions for king cobra that I've seen before include "venomous customer" , "enormous snake" , "Hooded giant" , "Large Asiatic snake" , "Venomous type" .)