Out loud, not many will be encouraging (4)
I believe the answer is:
fuel
'be encouraging' is the definition.
(fuel can mean to encourage or stimulate)
'out loud not many will' is the wordplay.
'out loud' indicates a 'sounds like' (homophone) clue.
'not many will' becomes 'few'll' (few will).
'fewll' sounds like 'FUEL'.
(Other definitions for fuel that I've seen before include "Material fed to flames" , "Power source; inflame" , "Substance to produce energy" , "Substance burned to source power" , "Eg, coal or oil" .)