Spare prop (4)

I believe the answer is:

lean

I believe this is a double definition.

'spare' is the first definition.
('lean' can be similar in meaning to 'spare')

'prop' is the second definition.
(thesaurus)

(Other definitions for lean that I've seen before include "Incline; (of person) thin" , "English film director" , "skinny" , "Slant" , "Containing little fat" .)

I've seen this clue in The Telegraph.

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