Loyal Pole in trouble in old city (14)
I believe the answer is:
constantinople
'old city' is the definition.
(I've seen this before)
'loyal pole in trouble' is the wordplay.
'loyal' becomes 'constant'.
'trouble' indicates anagramming the letters.
'pole'+'in'='polein'
'polein' is an anagram of 'inople'.
'constant'+'inople'='CONSTANTINOPLE'
'in' acts as a link.
(Other definitions for constantinople that I've seen before include "Old name of Istanbul" , "Old city" , "Former name of Istanbul" , "Istanbul formerly" , "capital no longer used" .)