A cleaner man was glum (5)
I believe the answer is:
moped
'glum' is the definition.
The answer and definition are different parts of speech. However, adjectives and past participle verbs occasionally define each other.
'a cleaner man' is the wordplay.
'a cleaner' becomes 'mop' (something which 'cleans').
'man' becomes 'Ed' (short for Edward).
'mop'+'ed'='MOPED'
'was' is the link.
Can you help me to learn more?
(Other definitions for moped that I've seen before include "sort of bike" , "Motor cycle -- sulked" , "Two-wheeled vehicle" , "Light motorbike" , "Was in low spirits about the low-powered motorbike" .)