Enclosed part of a blimp (7)
I believe the answer is:
nacelle
'enclosed part of a blimp' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nacelle that I've seen before include "airship's gondola" , "part of Jumbo" , "Aircraft body" , "Aircraft engine casing" , "Streamlined enclosure on aircraft" .)