Bird finds her working (5)
I believe the answer is:
heron
'bird' is the definition.
(heron is a kind of bird)
'her working' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'her'+'on'='HERON'
'finds' acts as a link.
(Other definitions for heron that I've seen before include "Large fish-eating bird" , "Bird of the Rhone, strangely" , "Big bird" , "Large British wading bird" , "Graceful grey bird with long neck" .)