Oddly poses as group of lawmen (5)
I believe the answer is:
posse
'group of lawmen' is the definition.
(I've seen this in another clue)
'oddly poses' is the wordplay.
'oddly' is an anagram indicator.
'poses' is an anagram of 'POSSE'.
'as' acts as a link.
(Other definitions for posse that I've seen before include "Group temporarily established for some purpose" , "Group supporting sheriff" , "Sheriff's band of men" , "power" , "Gang" .)