Attention shown without hesitation in a trial (8)
I believe the answer is:
interest
'attention' is the definition.
(thesaurus)
'without hesitation in a trial' is the wordplay.
'without' indicates putting letters inside.
'hesitation' becomes 'er' (sound made while hesitating - um, er).
'a trial' becomes 'test' ('test' can be a synonym of 'trial').
'in'+'test'='intest'
'er' going inside 'intest' is 'INTEREST'.
'shown' acts as a link.
(Other definitions for interest that I've seen before include "Fascinate" , "Pursuit" , "Profit" , "Sum paid on a loan" , "Share - concern" .)