Soft pencil is required for flyer (4)
I believe the answer is:
ibis
'for flyer' is the definition.
(type of bird)
'soft pencil is required' is the wordplay.
'soft pencil' becomes 'IB' (resembles 1B, a pencil with soft graphite).
'required' is a charade indicator (letters next to each other).
'ib'+'is'='IBIS'
(Other definitions for ibis that I've seen before include "sacred creature of Egypt" , "Near-colourless mineral" , "Retreat" , "State of central US, capital Lincoln" , "Hotel group" .)