There's hard work for him, Victor, in the navy (5)
I believe the answer is:
navvy
'there's hard work for him' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'victor in the navy' is the wordplay.
'victor' becomes 'V' (phonetic alphabet: alpha, bravo, charlie etc.).
'in the' is an insertion indicator.
'v' going inside 'navy' is 'NAVVY'.
Can you help me to learn more?
(Other definitions for navvy that I've seen before include "Construction labourer" , "Labourer working on canals, roads, railways etc?" , "Canal constructor" , "Canal labourer" , "Labourer, originally digging the canals" .)