Doctor with energy in the morning in Gateshead fantasising (8)
I believe the answer is:
dreaming
'fantasising' is the definition.
(I've seen this before)
'doctor with energy in the morning in gateshead' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'with' says to put letters next to each other.
'energy' becomes 'e' (physics symbol as in E=mcr).
'in the morning' becomes 'am' (AM on a clock).
'gateshead' becomes 'g' (head letter of 'gates').
'dr'+'e'+'am'+'in'+'g'='DREAMING'
(Other definitions for dreaming that I've seen before include "form of idealism?" , "Fantasising" , "'I'm ... of a white Christmas' (song)" , "Experiencing while sleeping" , "In reverie" .)