To jump is hot work (3)
I believe the answer is:
hop
'to jump' is the definition.
(hopping is a kind of jumping)
'hot work' is the wordplay.
'hot' becomes 'h'.
'work' becomes 'op' (abbreviation for opus).
'h'+'op'='HOP'
'is' is the link.
(Other definitions for hop that I've seen before include "Beer flavouring; jump" , "Jump on a pogo stick" , "Jump about on one leg" , "Dried flower; jump" , "Climbing plant - jump!" .)