Refined tempo shortened? Not altogether (4)
I believe the answer is:
posh
'refined' is the definition.
(I've seen this before)
'tempo shortened? not altogether' is the wordplay.
'not altogether' indicates a hidden word.
'POSH' is hidden within 'tempo shortened'.
(Other definitions for posh that I've seen before include "Stylishly luxurious" , "refined" , "Upper-class - Spice girl" , "Peterborough" , "U" .)