A specialist in education is lying (4)
I believe the answer is:
abed
'is lying' is the definition.
(lying abed or in bed)
'a specialist in education' is the wordplay.
'specialist in education' becomes 'BEd' (someone with a Bachelor of Education degree).
'a'+'bed'='ABED'
(Other definitions for abed that I've seen before include "in his hammock awaiting Santa?" , "how we all hope to go?" , "given blanket coverage?" , "having a lie-in?" , "at rest" .)