Henry left the building (4)
I believe the answer is:
hall
'the building' is the definition.
(hall is a kind of building)
'henry left' is the wordplay.
'henry' becomes 'hal' (short for Henry).
'left' becomes 'L' (common abbreviation).
'hal'+'l'='HALL'
(Other definitions for hall that I've seen before include "Large meeting room" , "Building used for public assembly" , "Large country house" , "College dinner; passage" , "See 1" .)