Whip-round for depressed area in the countryside (4,6)
I believe the answer is:
crop circle
'depressed area in the countryside' is the definition.
(indentation in a field)
'whip-round' is the wordplay.
'whip' becomes 'crop' (crop can mean a whip).
'round' becomes 'circle' (synonyms).
'crop'+'circle'='CROP CIRCLE'
'for' is the link.
(Other definitions for crop circle that I've seen before include "mysterious country area" , "Hertfordshire new town" .)