Blow the whistle on someone locally in hospital working in theatre (6)
I believe the answer is:
singer
'hospital working in theatre' is the definition.
I can't tell whether this definition defines the answer.
'blow the whistle on someone locally' is the wordplay.
'blow the whistle' becomes 'sing' (I've seen this before).
'on' says to put letters next to each other.
'someone locally' becomes 'er' (I can't justify this - if you can you should give a lot more credence to this answer).
'sing'+'er'='SINGER'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for singer that I've seen before include "Coventry car firm" , "Someone of note" , "Member of a choir" , "choirboy?" , "Musical sounds" .)