Salad vegetable in London skyscraper (7)
I believe the answer is:
gherkin
'salad vegetable' is the definition.
'gherkin' can be an answer for 'vegetable' (gherkin is a kind of vegetable). I'm not sure about the 'salad' bit.
'in london skyscraper' is the wordplay.
I cannot quite understand how this works, but
'in' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for gherkin that I've seen before include "Immature fruit of cucumber" , "Cucumber - London skyscraper" , "often pickled" , "Salad vegetable - City of London skyscraper" , "La traviata composer" .)