Frank is following on (7)
I believe the answer is:
sincere
'frank' is the definition.
(frank can mean sincere or honest)
'following on' is the wordplay.
'following' becomes 'since' (since can mean following or after).
'on' becomes 're' (regarding).
'since'+'re'='SINCERE'
'is' acts as a link.
(Other definitions for sincere that I've seen before include "Pure" , "straightforward" , "(Of person) genuine" , "Honest, frank" , "Unaffected" .)