Plastic bags Belgian hasn't opened, carrier of basket (3,7)

'carrier of basket' is the definition.
(as in a hot air balloon)

'plastic bags belgian hasn't opened' is the wordplay.
'plastic' indicates an anagram (plastic can mean easily moulded).
'belgian' becomes 'walloon' (Walloons are an ethnic group of Wallonia, Belgium).
'hasn't opened' means to remove the first letter (the letter which opens the word is removed).
'walloon' with its first letter taken off is 'alloon'.
'bags' with letters rearranged gives 'gasb'.
'gasb'+'alloon'='GAS BALLOON'