Airport said to allow Poles entry (8)
I believe the answer is:
stansted
'airport' is the definition.
(I've seen this before)
'said to allow poles entry' is the wordplay.
'said' becomes 'stated' ('state' can be a synonym of 'say').
'to allow poles' becomes 'ns' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'entry' indicates putting letters inside.
'stated' enclosing 'ns' is 'STANSTED'.
(Other definitions for stansted that I've seen before include "One of London's airports" , "Airport north of London" , "Departure point" .)