Embellish, rather, if being adopted (8)
I believe the answer is:
prettify
'embellish' is the definition.
(synonyms)
'rather if being adopted' is the wordplay.
'rather' becomes 'pretty' (synonyms).
'being adopted' indicates putting letters inside (inserted letters are adopted into the word).
'pretty' placed around 'if' is 'PRETTIFY'.
(Other definitions for prettify that I've seen before include "tart up" , "Make superficially attractive" , "Doll up" , "Ornament" .)