Sovereign the family start grabbing (4)
I believe the answer is:
king
'sovereign' is the definition.
(king is a kind of sovereign)
'family start grabbing' is the wordplay.
'family' becomes 'kin' (synonyms).
'start' indicates taking the first letters.
The initial letter of 'grabbing' is 'g'.
'kin'+'g'='KING'
'the' acts as a link.
(Other definitions for king that I've seen before include "initially unable to move" , "Chess piece" , "Honour for man" , "- Cobra; - crab; - post; - prawn" , "Card, draughts piece" .)