Bog area near central Ireland is rank (7)
I believe the answer is:
marshal
'is rank' is the definition.
(thesaurus)
'bog area near central ireland' is the wordplay.
'bog' becomes 'marsh' (I've seen this before**).
'area' becomes 'a' (maths abbreviation).
'near' is a charade indicator (letters next to each other).
'central' means to look at the middle letters.
The centre of 'ireland' is 'l'.
'marsh'+'a'+'l'='MARSHAL'
(Other definitions for marshal that I've seen before include "Bring together in order" , "Muster" , "Usher" , "High officer" , "High-ranking officer" .)