Be concerned about Liberal bore (7)
I believe the answer is:
calibre
'bore' is the definition.
(gun terminology)
'be concerned about liberal' is the wordplay.
'be concerned' becomes 'care' (caring about something is being concerned about it).
'about' indicates putting letters inside.
'liberal' becomes 'lib'.
'care' going around 'lib' is 'CALIBRE'.
(Other definitions for calibre that I've seen before include "Ability; barrel diameter" , "Diameter of bore of firearm" , "Diameter of bullet or shell" , "bore on the Tube?" , "Level of ability; bore" .)