Somehow teach unit to be reliable (9)
I believe the answer is:
authentic
'reliable' is the definition.
('authentic' can be a synonym of 'reliable')
'somehow teach unit' is the wordplay.
'somehow' is an anagram indicator.
'teach'+'unit'='teachunit'
'teachunit' anagrammed gives 'AUTHENTIC'.
'to be' is the link.
(Other definitions for authentic that I've seen before include "Genuine, not a copy" , "Real, genuine" , "Ian, the cut is genuine" , "24 [LEGIT]" , "reliable" .)