Congenial expense (8)
I believe the answer is:
outgoing
'congenial' is the definition.
(thesaurus)
'expense' is the wordplay.
I cannot quite see how this works, but
'expense' could be 'outgo' (I've seen this in another clue) and 'outgo' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for outgoing that I've seen before include "Expenditure" , "At ease in talking to others, extroverted" , "Extrovert" , "Friendly - retiring" , "open" .)