Lower number attached to name (6)
I believe the answer is:
nether
'lower' is the definition.
(as in nether regions)
'number attached to name' is the wordplay.
'number' becomes 'n' (n can represent any number).
'attached to' says to put letters next to each other.
'name' becomes 'ether' (I can't justify this - if you can you should believe this answer much more).
'n'+'ether'='NETHER'
(Other definitions for nether that I've seen before include "These garments are for the bottom half" , "Subordinate" , "Lower in position" , "Lower, like regions or garments" , "North European country" .)