Capital love letter read out (5)
I believe the answer is:
romeo
'letter read out' is the definition.
(NATO codeword)
'capital love' is the wordplay.
'capital' becomes 'rome' (capital of Italy).
'love' becomes 'o' (love means zero in tennis).
'rome'+'o'='ROMEO'
(Other definitions for romeo that I've seen before include "Peripheral figure" , "Ardent male lover" , "Juliet's swain" , "Juliet's lover of Verona" , "Amorous male" .)