Wife in bed: she may need briefs (6)
I believe the answer is:
lawyer
'she may need briefs' is the definition.
'wife in bed' is the wordplay.
'wife' becomes 'w'.
'in' is an insertion indicator.
'bed' becomes 'layer' (I've seen this before).
'w' going within 'layer' is 'LAWYER'.
(Other definitions for lawyer that I've seen before include "Legal practitioner" , "A solicitor, barrister or the like" , "Legal specialist" , "Legal professional" , "Legal eagle" .)