Small part of statistical report for firm (6)
I believe the answer is:
stable
'firm' is the definition.
(similar in meaning)
'small part of statistical report' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'part of statistical report' becomes 'table' (as in a table of data).
's'+'table'='STABLE'
'for' is the link.
(Other definitions for stable that I've seen before include "On an even keel" , "Jesus was born in one" , "Well balanced" , "Equine housing" , "Place of birth" .)