Fabled lion beginning to tip sideways (6)

I believe the answer is:

aslant

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'sideways' is the definition.
(thesaurus)

'fabled lion beginning to tip' is the wordplay.
'fabled lion beginning' becomes 'a' (I can't justify this - if you can you should believe this answer much more).
'to tip' becomes 'slant' ('slant' can be a synonym of 'tip').
'a'+'slant'='ASLANT'

Can you help me to learn more?

(Other definitions for aslant that I've seen before include "Out of the vertical" , "Obliquely" , "not on the level" , "Athwart" , "At an oblique angle" .)

I've seen this clue in The Sun.

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