Dishonourable chap recruited by spies for bug (6)
I believe the answer is:
cicada
'bug' is the definition.
(cicada is a type of insect)
'dishonourable chap recruited by spies' is the wordplay.
'dishonourable chap' becomes 'cad' (cad can mean a dishonourable person).
'recruited by' means one lot of letters goes inside another.
'spies' becomes 'CIA' (Central Intelligence Agency).
'cad' put inside 'cia' is 'CICADA'.
'for' is the link.
(Other definitions for cicada that I've seen before include "one that loves the heat" , "Large bug" , "Bug sounding at night" , "Insect, produces high-pitched drone" , "Large chirping insect" .)