Old militia do what a conductor might do (9)
I believe the answer is:
trainband
'old militia do' is the definition.
The definition suggests a singular noun which matches the answer.
'a conductor might do' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is found in the answer.
This explanation may well be incorrect...
'what' is the link.
Can you help me to learn more?
(Other definitions for trainband that I've seen before include "Members of militia" , "citizen soldiers?" , "Former militiamen" .)