Look for building to accommodate any number (4)
I believe the answer is:
hunt
'look for' is the definition.
(to hunt for something is to look for it)
'building to accommodate any number' is the wordplay.
'building' becomes 'hut' (type of small building).
'to accommodate' indicates putting letters inside.
'any number' becomes 'n' (mathematical symbol for an unspecified number).
'hut' enclosing 'n' is 'HUNT'.
(Other definitions for hunt that I've seen before include "Pursue (animal) for food or sport" , "Meet - famous mountaineer" , "Search (with dogs?)" , "F1 driver" , "track" .)