Carry on investing roubles in flutter (5)
I believe the answer is:
flirt
'carry on investing' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'roubles in flutter' is the wordplay.
'roubles' becomes 'R'.
'in' is an insertion indicator.
'flutter' becomes 'flit' (synonyms).
'r' inserted within 'flit' is 'FLIRT'.
Can you help me to learn more?
(Other definitions for flirt that I've seen before include "Hussy" , "Flutter one's eyelashes?" , "Coquet" , "Behave playfully with opposite sex" , "Be playfully amorous" .)