Sit around small group of lawmen (5)
I believe the answer is:
posse
'group of lawmen' is the definition.
(I've seen this in another clue)
'sit around small' is the wordplay.
'sit' becomes 'pose' (as in sitting for a painter).
'around' means one lot of letters goes inside another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'pose' enclosing 's' is 'POSSE'.
(Other definitions for posse that I've seen before include "Sheriff's team" , "Troop at the service of a local sheriff" , "Law-enforcers" , "Group supporting sheriff" , "power" .)