Song lifted Solo, spy lacking inside (7)
I believe the answer is:
calypso
'song' is the definition.
(I've seen this before)
'lifted solo spy lacking inside' is the wordplay.
'lifted' shows that the letters should be reversed in order (going up in down clue).
'inside' indicates the answer is hidden within the clue.
'ospylac' is hidden in the letters of 'solo spy lacking'.
'ospylac' back-to-front is 'CALYPSO'.
(Other definitions for calypso that I've seen before include "Ballad - dance - orchid - sea nymph - moon of Saturn" , "island song" , "Hostage-holding nymph" , "Caribbean satirical song" , "Satirical West Indian song and dance" .)