Note in favour of church is what keeps one down to earth (1-5)
I believe the answer is:
g-force
'what keeps one down to earth' is the definition.
I know nothing about this answer so I can't tell whether this works.
'note in favour of church' is the wordplay.
'note' becomes 'g' (musical note).
'in favour of' becomes 'for' (being for a particular cause).
'church' becomes 'CE' (abbreviation for Church of England).
'g'+'for'+'ce'='G-FORCE'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for g-force that I've seen before include "Unit exerted by gravity" , "Measure of acceleration due to gravity" .)