The hospital border? (5)
I believe the answer is:
hedge
'the hospital border?' is the definition.
'hedge' can be an answer for 'border?' (I have seen 'Border of vegetation ' mean 'hedge' so perhaps 'border' could also mean 'hedge'). I'm unsure of the 'the hospital' bit.
'hospital border?' is the wordplay.
'hospital' becomes 'H' (abbreviation for hospital).
'border?' becomes 'edge' ('edge' can be a synonym of 'border').
'h'+'edge'='HEDGE'
Can you help me to learn more?
(Other definitions for hedge that I've seen before include "Fence of bushes or small trees" , "Row of linked shrubs" , "Border of vegetation" , "Boundary of shrubs" , "sort of fund" .)