Analgesic property of tempo più mosso (5)
I believe the answer is:
opium
'analgesic' is the definition.
(I've seen this before)
'property of tempo piu mosso' is the wordplay.
'property of' indicates a hidden word (the answer is owned or contained by the clue).
'OPIUM' can be found hidden inside 'tempo piu mosso'.
(Other definitions for opium that I've seen before include "Derivative of Poppy" , "Narcotic drug" , "wars with China" , "Addictive narcotic" , "De Quincey confessed to eating it" .)