Relaxed as not spotted snatching rupees (10)
I believe the answer is:
'relaxed' is the definition.
(similar in meaning)
'not spotted snatching rupees' is the wordplay.
'not' becomes 'un' (prefix meaning 'not').
'spotted' becomes 'stained' ('stain' can be a synonym of 'spot').
'snatching' indicates putting letters inside.
'rupees' becomes 'r' (abbreviation for rupees).
'stained' placed around 'r' is 'strained'.
'as' is the link.
(Another definition for unstrained that I've seen is " relaxed".)