Former PM accepting Liberal constitution (6)
I believe the answer is:
health
'constitution' is the definition.
(I've seen this before)
'former pm accepting liberal' is the wordplay.
'former pm' becomes 'heath' (I've seen this before).
'accepting' indicates putting letters inside.
'liberal' becomes 'l' (abbreviation).
'heath' going around 'l' is 'HEALTH'.
(Other definitions for health that I've seen before include "Fine condition" , "Clinician's concern - toasted condition?" , "Good condition" , "constitution" , "State of well-being" .)