Exasperation when serving tea with a smile (7)
I believe the answer is:
chagrin
'exasperation' is the definition.
(chagrin can mean exasperation or annoyance)
'tea with a smile' is the wordplay.
'tea' becomes 'cha' (cha is a type of tea).
'with' is a charade indicator (letters next to each other).
'a smile' becomes 'grin' (synonyms).
'cha'+'grin'='CHAGRIN'
'when serving' is the link.
(Other definitions for chagrin that I've seen before include "Arching with annoyed disappointment" , "Annoyance at having been humiliated" , "Acute annoyance or disappointment" , "anything but delight" , "Annoy" .)