Casual worker delayed making model (8)
I believe the answer is:
template
'model' is the definition.
(I know that template is a type of model)
'casual worker delayed' is the wordplay.
'casual worker' becomes 'temp' (short-term or temporary worker).
'delayed' becomes 'late' (running late).
'temp'+'late'='TEMPLATE'
'making' acts as a link.
(Other definitions for template that I've seen before include "Model, example to follow" , "Model or standard for making comparisons" , "original design" , "Preset file or document format" , "Shape serving as model" .)