Good artist to celebrate coming up step-by-step (7)
I believe the answer is:
gradual
'step-by-step' is the definition.
('gradual' can be similar in meaning to 'step-by-step')
'good artist to celebrate coming up' is the wordplay.
'good' becomes 'g' (abbreviation).
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'to celebrate' becomes 'laud' (I've seen this before).
'coming up' shows that the letters should be reversed in order.
'laud' reversed gives 'dual'.
'g'+'ra'+'dual'='GRADUAL'
(Other definitions for gradual that I've seen before include "Continuous" , "(Of slope) not steep" , "By slow degrees" , "Developing in small steps" , "Step by step" .)