Secure small item of furniture (6)
I believe the answer is:
stable
'secure' is the definition.
(thesaurus)
'small item of furniture' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'item of furniture' becomes 'table' (I've seen this before).
's'+'table'='STABLE'
(Other definitions for stable that I've seen before include "Solid" , "Fixed; secure" , "Not wobbly" , "Settled; animal shed" , "Horse establishment" .)