So Vera's content to work (4)
I believe the answer is:
ergo
'so' is the definition.
('ergo' can be a synonym of 'so')
'vera's content to work' is the wordplay.
'content' indicates the central letters.
'to work' becomes 'go' ('go' can be a synonym of 'work').
The centre of 'vera' is 'er'.
'er'+'go'='ERGO'
(Other definitions for ergo that I've seen before include "'Cogito, ---- sum'" , "so philosopher wrote in Latin" , "Hence" , "as a consequence" , "It follows" .)