Ridicule working model not out of bed? (4)
I believe the answer is:
mock
'ridicule' is the definition.
(thesaurus)
'working model not out of bed?' is the wordplay.
'working model' becomes 'mockup' (I've seen this before).
'not' is a deletion indicator.
'out of bed?' becomes 'up' ('up' can be a synonym of 'out of bed').
'mockup' with 'up' taken away is 'MOCK'.
(Other definitions for mock that I've seen before include "Scoff at" , "Faux - take the mickey" , "Treat with contempt -- imitation" , "Deride - false" , "Make fun of; imitation" .)