He sings a number in the latter half (5)
I believe the answer is:
tenor
'he sings a' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'number in the latter half' is the wordplay.
'number' becomes 'no' (abbreviation for 'number').
'in the' is an insertion indicator.
'half' suggests halving the letters.
'latter' with half the letters taken is 'ter'.
'no' going within 'ter' is 'TENOR'.
Can you help me to learn more?
(Other definitions for tenor that I've seen before include "Singer (one of three?)" , "exact words" , "Pavarotti, for example" , "Caruso or Domingo" , "One singing" .)