Society which admits inexperienced boater for one (5,3)
I believe the answer is:
straw hat
'boater for one' is the definition.
(a boater is a type of straw hat)
'society which admits inexperienced' is the wordplay.
'society' becomes 's' (common abbreviation in names of organisations).
'which' becomes 'that'.
'admits' means one lot of letters goes inside another.
'inexperienced' becomes 'raw' ('raw' can be similar in meaning to 'inexperienced').
'that' placed around 'raw' is 'trawhat'.
's'+'trawhat'='STRAW-HAT'
(Other definitions for straw hat that I've seen before include "Capital Investment?"" , "Panama" , "Boater" .)