Service one's given when one leaves unhappy (8)
I believe the answer is:
evensong
'service' is the definition.
(type of church service)
'one's given when one leaves unhappy' is the wordplay.
I cannot really see how this works, but
'when' could be 'on' (I've seen this in other clues) and 'on' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for evensong that I've seen before include "... Prayers" , "Late afternoon church service" , "Anglican service" , "Vespers" , "Service of evening prayer in Church of England" .)