Adam's partner right always (4)
I believe the answer is:
ever
'always' is the definition.
(synonyms)
'adam's partner right' is the wordplay.
'adam's partner' becomes 'eve' (in the Garden of Eden).
'right' becomes 'r' (common abbreviation).
'eve'+'r'='EVER'
(Other definitions for ever that I've seen before include "Perpetually" , "Veer away endlessly" , "To the end of time" , "constantly" , "In perpetuity" .)