It takes a month to get round the county (4)
I believe the answer is:
mayo
'county' is the definition.
(county of Ireland)
'it takes a month to get round' is the wordplay.
'it' becomes 'y' (I can't justify this - if you can you should believe this answer much more).
'takes' means one lot of letters goes inside another (take can mean to capture or invade).
'month' becomes 'mo' (abbreviation for month).
'to get round' is an insertion indicator.
'a' put inside 'mo' is 'mao'.
'y' placed inside 'mao' is 'MAYO'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for mayo that I've seen before include "radio presenter" , "County of Western Eire" , "Ir. county; salad dressing" , "County of north-west Ireland" , "You'll find it in the Emerald Isle" .)