Being generous, a number lash out (6)
I believe the answer is:
lavish
'being generous' is the definition.
('lavish' can be similar in meaning to 'generous')
'a number lash out' is the wordplay.
'a number' becomes 'vi' (VI is an example**).
'out' is an insertion indicator.
'vi' put into 'lash' is 'LAVISH'.
(Other definitions for lavish that I've seen before include "Prodigal - unrestrained" , "Lash around Vi is extravagant (6)" , "Extremely generous" , "Extravagant or excessive" , "Rich, elaborate" .)