Gunmen joke about tense rabble (6)
I believe the answer is:
ragtag
'rabble' is the definition.
(I know that rabble can be written as ragtag)
'gunmen joke about tense' is the wordplay.
'gunmen' becomes 'RA' (Royal Artillery).
'joke' becomes 'gag' (a gag is a joke or witticism).
'about' is an insertion indicator.
'tense' becomes 't' (abbreviation used in many dictionaries).
'gag' enclosing 't' is 'gtag'.
'ra'+'gtag'='RAGTAG'
(Other definitions for ragtag that I've seen before include "Masses" , "hoi polloi" , "Disreputable group of people" , "Badly organised" , "Common people, riff-raff - ...... and bobtail" .)