He takes over unruly road pet (7)
I believe the answer is:
adopter
'he takes over' is the definition.
The definition suggests a singular noun which matches the answer.
'unruly road pet' is the wordplay.
'unruly' indicates anagramming the letters.
'road'+'pet'='roadpet'
'roadpet' anagrammed gives 'ADOPTER'.
Can you help me to learn more?
(Other definitions for adopter that I've seen before include "who extends a family welcome?" , "person to accept another's child?" , "Person taking legal responsibility for a child not biologically theirs" , "One may take issue" , "A redtop (anag.)" .)