Wandering figure adopting new set unexpectedly (9)

I believe the answer is:
strangely
'unexpectedly' is the definition.
Both the definition and answer are adverbs. Perhaps they are linked in a way I don't understand?
'wandering figure adopting new set' is the wordplay.
'wandering figure' becomes 'stray' (I am not sure about this - if you are sure you should believe this answer much more).
'adopting' means one lot of letters goes inside another (inserted letters are taken on or adopted).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'set' becomes 'gel' (both can mean to harden).
'n'+'gel'='ngel'
'stray' going around 'ngel' is 'STRANGELY'.
Can you help me to learn more?
(Other definitions for strangely that I've seen before include "Oddly, queerly" , "In an odd way" , "Weirdly" , "Oddly, curiously" , "unusually" .)
