Worked at reception with energy; tired at the end (10)

'worked' is the definition.
('function' can be a synonym of 'work')

'at reception with energy tired at the end' is the wordplay.
I cannot quite see how this works, but
'at' could be 'on' (location) and 'on' is present in the answer.
'energy' could be 'e' (physics symbol as in E=mc2) and 'e' is found in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?