Gallery set out in grand style (7)
I believe the answer is:
regally
'out in grand style' is the definition.
Both the definition and answer are adverbs. Maybe they are linked in a way I don't understand?
'gallery set' is the wordplay.
'set' indicates anagramming the letters (instruction to set the letters).
'gallery' is an anagram of 'REGALLY'.
Can you help me to learn more?
(Other definitions for regally that I've seen before include "in great style" , "In royal fashion" , "Largely in royal manner" , "Like a monarch" , "as befits monarch" .)