Lose energy from calling nurse (5)
I believe the answer is:
carer
'nurse' is the definition.
(I've seen this before)
'lose energy from calling' is the wordplay.
I cannot really understand how this works, but
'energy' could be 'e' (physics symbol as in E=mc2) and 'e' is located in the answer.
The remaining letters 'carr' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
(Other definitions for carer that I've seen before include "Racer (anag.)" , "One looking after an incapacitated person" , "Person who attends to a dependent adult" , "One looking after another" , "Nurse's vocation" .)