Lately, carrier bags have proved essential in workshop (7)
I believe the answer is:
atelier
'workshop' is the definition.
(workshop used by a designer or artist)
'lately carrier bags have proved essential' is the wordplay.
I cannot really understand how this works, but
'carrier' could be 'el' (el is a kind of carrier) and 'el' is present in the answer.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for atelier that I've seen before include "Artist's studio (French)" , "Artist's workshop, studio" , "Artist's workroom" , "I relate to workshop used by artist" , "Tie earl up in the artist's place" .)