Regret about an eastern monarchy spinning charm (7)
I believe the answer is:
enamour
'charm' is the definition.
(I know that charm can be written as enamour)
'regret about an eastern monarchy spinning' is the wordplay.
'regret' becomes 'rue' (to rue something is to regret it).
'about' means one lot of letters goes inside another.
'an eastern monarchy' becomes 'Oman' (Oman is a monarchy in the Middle East).
'spinning' says the letters should be written backwards.
'rue' placed around 'oman' is 'ruomane'.
'ruomane' in reverse letter order is 'ENAMOUR'.
(Other definitions for enamour that I've seen before include "Delight" , "entrance" , "Fill with love" , "Enchant" , "Our name (anag)" .)