Dali working with a stick about injection moulding (4,4)

'moulding' is the definition.
(moulding running around a room)

'dali working with a stick about injection' is the wordplay.
'working with' is an anagram indicator (working with the letters).
'stick' becomes 'rod' (I've seen this in another clue).
'about' says the letters should be written in reverse.
'injection' means one lot of letters goes inside another.
'a'+'rod'='arod'
'arod' written backwards gives 'dora'.
'dali' anagrammed gives 'dail'.
'dail' placed around 'dora' is 'DADO RAIL'.