Bowl first of bumpers when at home (5)
I believe the answer is:
basin
'bowl' is the definition.
(synonyms)
'first of bumpers when at home' is the wordplay.
'first of bumpers' becomes 'b' (1st letter of 'bumpers').
'when' becomes 'as'.
'at home' becomes 'in' (similar in meaning).
'b'+'as'+'in'='BASIN'
(Other definitions for basin that I've seen before include "Bowl-shaped vessel" , "Kitchen vessel" , "Area drained by a river" , "Sink for washing" , "Depression in the earth's surface" .)