Caught greeting in hollow (4)
I believe the answer is:
cave
'hollow' is the definition.
(caving is a kind of hollowing)
'caught greeting' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'greeting' becomes 'ave' (I've seen this before).
'c'+'ave'='CAVE'
'in' acts as a link.
(Other definitions for cave that I've seen before include "Watch out" , "Large grotto" , "Underground enclosure with surface access" , "part of rocky coastline?" , "Hollow in a rock" .)