He performs first in a tear-jerker (7)
I believe the answer is:
artiste
'he performs' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'first in a tear-jerker' is the wordplay.
'first' becomes 'ist' (ist resembles ast).
'in' is an insertion indicator.
'a tear jerker' becomes 'arte' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ist' put into 'arte' is 'ARTISTE'.
Can you help me to learn more?
(Other definitions for artiste that I've seen before include "Entertainer, singer or dancer" , "Trouper" , "Attires for professional entertainer" , "Professional performer" , "nightclub entertainer?" .)