One harvesting fish circling at a particular point (8)
I believe the answer is:
gatherer
'one harvesting' is the definition.
(I know that gatherer often perform the action glean)
'fish circling at a particular point' is the wordplay.
'fish' becomes 'gar' (type of gar).
'circling' means one lot of letters goes inside another (circling can mean going around or containing).
'at a particular point' becomes 'there'.
'gar' enclosing 'there' is 'GATHERER'.
(Other definitions for gatherer that I've seen before include "One collecting eg plants for subsistence" , "Collector" .)