Small note accompanying love letter from overseas (7)
I believe the answer is:
omicron
'from overseas' is the definition.
I can't tell whether this defines the answer.
'small note accompanying love letter' is the wordplay.
'small' becomes 'micro' (similar in meaning).
'note' becomes 'n' (abbreviation).
'accompanying' says to put letters next to each other.
'love letter' becomes 'o' (the letter O resembles 0, or 'love' in tennis).
'micro'+'n'='micron'
'micron' put after 'o' is 'OMICRON'.
Can you help me to learn more?
(Other definitions for omicron that I've seen before include "Fifteenth letter of the Greek alphabet" , "15th letter of the Greek alphabet" , "old letter" , "Olympic character" , "Greek character" .)