What Jacob was? Leader of House — stuffy with it (8)
I believe the answer is:
hairless
'what jacob was?' is the definition.
(as opposed to his hairy brother Esau in the Bible)
'leader of house stuffy with it' is the wordplay.
'leader of' says to take the initial letters.
'stuffy' becomes 'airless' (synonyms).
'with it' is a charade indicator (letters next to each other).
The first letter of 'house' is 'h'.
'h'+'airless'='HAIRLESS'
(Other definitions for hairless that I've seen before include "Furious" , "suffering shock loss" , "Bald" .)