Choose isolated area for a dip (10)
I believe the answer is:
pickpocket
'for a dip' is the definition.
('pickpocket' can be a synonym of 'dip')
'choose isolated area' is the wordplay.
'choose' becomes 'pick' (picking is a kind of choosing).
'isolated area' becomes 'pocket'.
'pick'+'pocket'='PICKPOCKET'
(Other definitions for pickpocket that I've seen before include "Thief working in public places" , "Cutpurse" , "Tea leaf" , "Dip" , "Artful Dodger?" .)