Church without members is low on appeal (9)
I believe the answer is:
charmless
'low on appeal' is the definition.
(without charm or appeal)
'church without members' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'without members' becomes 'armless' ('member' can be 'arm' (member can mean a limb) so maybe 'without members' can be ''armless').
'ch'+'armless'='CHARMLESS'
'is' acts as a link.
(Other definitions for charmless that I've seen before include "Without attractive features" , "not winning" , "Unattractive" , "Lacking any appeal" .)