Apply pressure on former husband to avoid Perth outskirts (5)
I believe the answer is:
exert
'apply' is the definition.
(exerting is a kind of applying)
'pressure on former husband to avoid perth outskirts' is the wordplay.
I cannot quite see how this works, but
'former' could be 'ex' (prefix meaning former or onetime) and 'ex' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for exert that I've seen before include "Apply (pressure)" , "Bring quality or influence into play" , "Bring into play, wield" , "Bring into operation" , "Expend" .)