Search isle: nitrogen found in shed (7)
I believe the answer is:
manhunt
'search' is the definition.
(I know that manhunt is a type of search)
'isle nitrogen found in shed' is the wordplay.
'isle' becomes 'man' (the Isle of Man is an example).
'nitrogen' becomes 'N' (N is the chemical symbol for nitrogen).
'found in' indicates putting letters inside.
'shed' becomes 'hut' (I've seen this in another clue).
'n' put inside 'hut' is 'hunt'.
'man'+'hunt'='MANHUNT'
(Other definitions for manhunt that I've seen before include "Search for criminal" , "in which one wanted to be found?" , "Police search operation" , "Pursuit of missing person" , "Organised search for a fugitive" .)