Ended unreliable trade given excessive merit (9)
I believe the answer is:
overrated
'given excessive merit' is the definition.
(I've seen this before)
'ended unreliable trade' is the wordplay.
'ended' becomes 'over' (synonyms).
'unreliable' is an anagram indicator.
'trade' with letters rearranged gives 'rated'.
'over'+'rated'='OVERRATED'
(Other definitions for overrated that I've seen before include "Given excessive merit" , "Thought too highly of" , "Too highly esteemed" , "Valued too highly, not as good as believed to be" .)