Stomach the first piece of music I had to play repeatedly (7)
I believe the answer is:
midriff
'stomach' is the definition.
(I've seen this before)
'first piece of music i had to play repeatedly' is the wordplay.
'first piece of' says to take the initial letters.
'i had' becomes 'I'd' (contraction).
'to play repeatedly' becomes 'riff' (as in playing a musical riff).
The initial letter of 'music' is 'm'.
'm'+'id'+'riff'='MIDRIFF'
'the' acts as a link.
(Other definitions for midriff that I've seen before include "Waistline area" , "Tummy area" , "Diaphragm area" , "Part of torso" , "Part of body between waist and chest" .)