Shut up a second! B___ stopping? I hope he is (6)
I believe the answer is:
gasbag
'i hope he is' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'shut up a second b stopping?' is the wordplay.
'shut up' becomes 'gag' (gagging is a kind of shutting up).
'a second' becomes 'as' (I've seen this in other clues**).
'stopping?' indicates putting letters inside (stopping can mean blocking a gap).
'as'+'b'='asb'
'gag' enclosing 'asb' is 'GASBAG'.
(Other definitions for gasbag that I've seen before include "I can't shut up" , "goes on and on" , "Chatterbox" , "I talk too much" , "This can be elevating" .)