Account by a young person should be reliable (8)
I believe the answer is:
accurate
'reliable' is the definition.
(similar in meaning)
'account by a young person' is the wordplay.
'account' becomes 'ac' (abbreviation for account).
'by' says to put letters next to each other.
'a young person' becomes 'curate' (curate is a kind of person. I am not sure about the 'young' bit.).
'ac'+'curate'='ACCURATE'
'should be' is the link.
Can you help me to learn more?
(Other definitions for accurate that I've seen before include "carefully and precisely" , "Care a cut is exact" , "Totally correct" , "faithful" , "Careful, precise" .)