Former Uber worker is full of life (9)
I believe the answer is:
exuberant
'full of life' is the definition.
(exuberant means full of energy or life)
'former uber worker' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'worker' becomes 'ant' (worker is a type of ant).
'ex'+'uber'+'ant'='EXUBERANT'
'is' is the link.
(Other definitions for exuberant that I've seen before include "Exeunt bar, being in high spirits" , "Full of energy, high spirits" , "Full of beans" , "Enthusiastic" , "Vivacious; effusive" .)