Fairly good getting brought up outside capital finally — being taken outside London, say? (13)

'taken outside london say?' is the definition.
The answer and definition can be both related to change as well as being past participle verbs.
Perhaps you can see an association between them that I don't see?

'fairly good getting brought up outside capital finally' is the wordplay.
'fairly good' becomes 'decent' (I've seen this before).
'getting' says to put letters next to each other.
'brought up' becomes 'raised' ('raise' can be a synonym of 'bring up').
'outside' means one lot of letters goes inside another (some letters go outside others).
'capital finally' becomes 'l' (I can't explain this - if you can you should believe this answer much more).
'raised' enclosing 'l' is 'ralised'.
'decent'+'ralised'='DECENTRALISED'

'being' is the link.

Can you help me to learn more?