Very small letter and flower personal assistant dismissed (6)
I believe the answer is:
teensy
'very small' is the definition.
(teensy means very small)
'letter and flower personal assistant dismissed' is the wordplay.
I cannot quite see how this works, but
'letter' could be 'en' (I've seen this in other clues) and 'en' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for teensy that I've seen before include "Tiny" , "- - -weensy" , "Minute" , "Mini" , "Very small" .)