Large heat developed in machine (5)
I believe the answer is:
lathe
'machine' is the definition.
(machine for shaping metal etc)
'large heat developed in' is the wordplay.
'large' becomes 'l' (eg in clothes sizes).
'developed' indicates anagramming the letters.
'in' means one lot of letters goes inside another.
'heat' with letters rearranged gives 'athe'.
'l' going within 'athe' is 'LATHE'.
(Other definitions for lathe that I've seen before include "Wood-shaping machine" , "Turning instrument" , "piece of machinery" , "Turning tool" , "8 [TURNER]" .)