According to reporter, East End trio's at large (4)
I believe the answer is:
free
'at large' is the definition.
(similar in meaning)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for free that I've seen before include "without payment" , "Rescue" , "Under no obligation" , "Reef (anag.)" , "Not under restraint" .)