He cometh in play or cinema production (6)
I believe the answer is:
iceman
'he cometh in play' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'cinema production' is the wordplay.
'production' indicates an anagram.
'cinema' is an anagram of 'ICEMAN'.
'or' is the link.
Can you help me to learn more?
(Other definitions for iceman that I've seen before include "He delivers" , "Cold character in cinema" , "'The ------ Cometh', 1939 play by Eugene O'Neill" , "Professional killer - jewel thief - Eugene O'Neill character" , "assassin" .)