Love song composed about the present time (8)
I believe the answer is:
serenade
'love song' is the definition.
(a serenade might be sung to a lover)
'composed about the present time' is the wordplay.
'composed' becomes 'serene' (I've seen this in another clue).
'about' means one lot of letters goes inside another.
'the present time' becomes 'AD' (AD, Anno Domini, as opposed to BC, Before Christ).
'serene' going around 'ad' is 'SERENADE'.
(Other definitions for serenade that I've seen before include "Suitor's song" , "Noted performance" , "Piece sung beneath beloved's window" , "Piece of music for lovers at night" , "Lover's song" .)