Spoil hot iron with constant temperature (6)
I believe the answer is:
infect
'spoil' is the definition.
Although both the answer and definition are verbs in their base form, I don't see how one could define the other.
'hot iron with constant temperature' is the wordplay.
'hot' becomes 'in' (both can mean fashionable).
'iron' becomes 'Fe' (chemical symbol for iron).
'with' is a charade indicator (letters next to each other).
'constant' becomes 'c' (common symbol in maths for an unknown constant).
'temperature' becomes 't' (abbreviation).
'in'+'fe'+'c'+'t'='INFECT'
Can you help me to learn more?
(Other definitions for infect that I've seen before include "Contaminate with disease" , "Transmit disease to another" , "Impart a disease" , "Contaminate, make ill" , "Cause sickness (with a virus)" .)