Crawler's joined religious faction! (6)
I believe the answer is:
insect
'crawler's' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'joined religious faction?' is the wordplay.
'joined religious' becomes 'in' (I can't explain this - if you can you should believe this answer much more).
'faction?' becomes 'sect' ('sect' can be a synonym of 'faction').
'in'+'sect'='INSECT'
Can you help me to learn more?
(Other definitions for insect that I've seen before include "Contemptible person" , "For example, fly" , "cricket, say" , "A fly, for instance" , "Eg, beetle or fly" .)