Just receiving training in public (6)
I believe the answer is:
openly
'in public' is the definition.
(I've seen this before)
'just receiving training' is the wordplay.
'just' becomes 'only' (synonyms).
'receiving' means one lot of letters goes inside another.
'training' becomes 'pe'.
'only' going around 'pe' is 'OPENLY'.
(Other definitions for openly that I've seen before include "In frank and candid manner" , "Without concealment, frankly" , "In public" , "(Done) without concealment" , "Candidly, without concealment." .)