Greenery a bind when invading shelter (7)

I believe the answer is:

leafage

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'greenery' is the definition.
(I've seen this before)

'a bind when invading shelter' is the wordplay.
'bind when' becomes 'fag' (I can't justify this - if you can you should believe this answer much more).
'invading' means one lot of letters goes inside another.
'shelter' becomes 'lee' (as in lee side, the side sheltered from wind).
'a'+'fag'='afag'
'afag' placed within 'lee' is 'LEAFAGE'.

Can you help me to learn more?

(Other definitions for leafage that I've seen before include "Greenery" , "Foliage" , "Gala fee (anag)" , "marijuana, possibly" , "Green growth" .)

I've seen this clue in The Times.

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