Sampled before and trusted to be reliable (5)
I believe the answer is:
tried
This clue could be a double definition.
'sampled' is the first definition.
('try' can be a synonym of 'sample')
'be reliable' is the second definition.
(similar in meaning)
'before and trusted to' is the link.
I am not very happy about this link. Some or all of it may belong to one of the definitions.
Can you help me to learn more?
(Other definitions for tried that I've seen before include "Made an effort" , "Tested" , "Sampled" , "Had a crack" , "Endeavoured" .)