Oscar uses a hot tumbling drier (4-5)
I believe the answer is:
oast-house
'drier' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see a link between them that I can't see?
'oscar uses a hot tumbling' is the wordplay.
'oscar' becomes 'O' (phonetic alphabet: alpha, bravo, charlie etc.).
'tumbling' indicates an anagram.
'uses'+'a'+'hot'='usesahot'
'usesahot' with letters rearranged gives 'asthouse'.
'o'+'asthouse'='OAST-HOUSE'
Can you help me to learn more?
(Other definitions for oast-house that I've seen before include "Building containing kilns" , "Kent dwelling" , "Building where hops are dried" .)