Estimable person painting piece of furniture (7)
I believe the answer is:
ratable
'estimable' is the definition.
(able to be rated or estimated)
'person painting piece of furniture' is the wordplay.
'person painting' becomes 'RA' (Royal Academician, member of the Royal Academy).
'piece of furniture' becomes 'table' (table is a kind of piece of furniture).
'ra'+'table'='RATABLE'
(Other definitions for ratable that I've seen before include "may be estimated" , "subject to a local tax" , "worthy of respect" , "may be given value" , "may have price put on it" .)