Griselda not as jumpy in plane (6)
I believe the answer is:
glider
'plane' is the definition.
(glider is a type of plane)
'griselda not as jumpy' is the wordplay.
'not' suggests deleting specific letters.
'jumpy' indicates an anagram (letters jumping around).
'griselda' with 'as' taken away is 'grield'.
'grield' with letters rearranged gives 'GLIDER'.
'in' is the link.
(Other definitions for glider that I've seen before include "Sailplane" , "quiet flier" , "Unpowered plane" , "Unpowered aircraft" , "Girdle for silent flier" .)