Pasty initially expelled after a tiny bit (5)
I believe the answer is:
white
'pasty' is the definition.
(thesaurus)
'initially expelled after a tiny bit' is the wordplay.
'initially' says to take the initial letters.
'after' says to put letters next to each other.
'a tiny bit' becomes 'whit' (as in 'not a whit').
The first letter of 'expelled' is 'e'.
'e' after 'whit' is 'WHITE'.
(Other definitions for white that I've seen before include "Wit, he? (anag.)" , "murderer" , "Very pale; morally pure" , "Reflecting virtually all light" , "Chess player moving first" .)