Teach unit about being genuine (9)
I believe the answer is:
authentic
'being genuine' is the definition.
(similar in meaning)
'teach unit about' is the wordplay.
'about' indicates anagramming the letters.
'teach'+'unit'='teachunit'
'teachunit' anagrammed gives 'AUTHENTIC'.
(Other definitions for authentic that I've seen before include "trustworthy" , "24 [LEGIT]" , "reliable" , "Ian, the cut is genuine" , "Real, genuine" .)