Group one's seen around venues (5)
I believe the answer is:
sites
'venues' is the definition.
(I've seen this in another clue)
'group one's seen around' is the wordplay.
'group' becomes 'set' (both can mean a collection).
'one's' becomes 'is' (Roman numeral).
'seen around' shows that the letters should be reversed in order.
'set'+'is'='setis'
'setis' backwards is 'SITES'.
(Other definitions for sites that I've seen before include "Locates" , "places" , "Is set among building locations" , "Is set (anag)" , "internet locations" .)