Vitality, enthusiasm (5)
(Other definitions for verve that I've seen before include "Energy and zest" , "zip" , "Sparkling enthusiasm" , "Animation" , "Great liveliness or enthusiasm" .)
This clue is a double definition.
'vitality' is the first definition.
(I've seen this before)
'enthusiasm' is the second definition.
(I've seen this before)
(Other definitions for oomph that I've seen before include "Vitality - sex appeal (informal)" , "Shows excitement aplenty" , "Get-up-and-go" , "sex-appeal" , "15 [SEXINESS]" .)