Secretary I encountered in park, unusually hot stuff! (7)
I believe the answer is:
paprika
'hot stuff' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'secretary i encountered in park unusually' is the wordplay.
'secretary' becomes 'pa' (abbreviation for personal assistant).
'encountered in' is an insertion indicator.
'unusually' indicates an anagram.
'park' with letters rearranged gives 'prka'.
'i' going within 'prka' is 'prika'.
'pa'+'prika'='PAPRIKA'
Can you help me to learn more?
(Other definitions for paprika that I've seen before include "Spice used in goulash" , "Hot powder" , "Powdered pimiento" , "Powder made from dried red pepper" , "Powdered hot spice" .)