Tenant perhaps, full of energy, to go in again (2-5)
I believe the answer is:
re-enter
'go in again' is the definition.
(I've seen this before)
'tenant perhaps full of energy' is the wordplay.
'tenant perhaps' becomes 'renter' (someone renting a property).
'full of' is an insertion indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'renter' placed around 'e' is 'RE-ENTER'.
'to' acts as a link.
(Other definitions for re-enter that I've seen before include "compete again" , "Go back in" , "Come back inside" , "Come or go in again" .)