Way old Jack returns, at a gentle speed (8)
I believe the answer is:
moderato
'at a gentle speed' is the definition.
I can't judge whether this definition defines the answer.
'way old jack returns' is the wordplay.
'way' becomes 'mode' (synonyms).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'jack' becomes 'tar' (both are informal terms for sailor).
'returns' shows that the letters should be reversed in order.
'o'+'tar'='otar'
'otar' written backwards gives 'rato'.
'mode'+'rato'='MODERATO'
Can you help me to learn more?
(Other definitions for moderato that I've seen before include "with steady movement" , "at a medium pace" , "Musically fairly slow" , "not too fast, not too slow" , "At an average pace (music)" .)