Quiet girl's taken on in Irish airport (7)
I believe the answer is:
shannon
'irish airport' is the definition.
(I've seen this before)
'quiet girl's taken on' is the wordplay.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'girl' becomes 'ann' (woman's name).
'taken' is a charade indicator (letters next to each other).
'sh'+'ann'+'on'='SHANNON'
'in' acts as a link.
(Other definitions for shannon that I've seen before include "Irish 10" , "Major Irish river" , "One who rendered runaway" , "Ireland's longest river" , "Long-distance runner" .)