Small, trim and thin (5)

I believe the answer is:

spare

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

'small trim' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'trim' becomes 'pare' (I've seen this before).
's'+'pare'='SPARE'

'and' is the link.

(Other definitions for spare that I've seen before include "In reserve; pardon" , "With no excess fat" , "Leftover" , "Not required" , "Pardon; unneeded" .)

I've seen this clue in the Evening Standard.

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