Father returned and concealed bug (5)
I believe the answer is:
aphid
'bug' is the definition.
(I've seen this before)
'father returned and concealed' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'returned' says the letters should be written backwards.
'and' is a charade indicator (letters next to each other).
'concealed' becomes 'hid' ('hide' can be a synonym of 'conceal').
'pa' back-to-front is 'ap'.
'ap'+'hid'='APHID'
(Other definitions for aphid that I've seen before include "plant pest" , "Sap-sucking bug" , "Horticultural pest" , "Blackfly or greenfly" , "Small plant-sucking insect" .)