Mould made by casual worker behind schedule (8)
I believe the answer is:
template
'mould' is the definition.
(thesaurus)
'by casual worker behind schedule' is the wordplay.
'by' means one lot of letters go next to another.
'casual worker' becomes 'temp' (short-term or temporary worker).
'behind schedule' becomes 'late' (running late).
'temp'+'late' is 'TEMPLATE'.
'made' acts as a link.
(Other definitions for template that I've seen before include "Pattern or mould" , "Model, example to follow" , "Something used as a pattern" , "Pattern shape" , "Shaped pattern" .)