Becoming cunning about oriental compiler's return (6)
I believe the answer is:
seemly
'becoming' is the definition.
('seemly' can be a synonym of 'becoming')
'cunning about oriental compiler's return' is the wordplay.
'cunning' becomes 'sly' ('sly' can be a synonym of 'cunning'**).
'about' is an insertion indicator.
'oriental' becomes 'e'.
'compiler' becomes 'me' (the person who is writing these clues).
'return' shows that the letters should be reversed in order.
'me' in reverse letter order is 'em'.
'e'+'em'='eem'
'sly' going around 'eem' is 'SEEMLY'.
(Other definitions for seemly that I've seen before include "Proper, in good taste" , "Decent - handsome" , "Decorous, in good taste" , "Fitting" , "Decorous or proper" .)