Outlaws devouring eggs, at first, then heads (5)
I believe the answer is:
beans
'heads' is the definition.
(bean is a kind of head)
'outlaws devouring eggs at first' is the wordplay.
'outlaws' becomes 'bans' (banning is a kind of outlawing).
'devouring' is an insertion indicator.
'at first' says to take the initial letters.
The initial letter of 'eggs' is 'e'.
'bans' going around 'e' is 'BEANS'.
'then' acts as a link.
(Other definitions for beans that I've seen before include "Nothing at all in US" , "nuts" , "Coffee seeds" , "Haricots, e.g." , "Haricots for instance" .)