Transport service puts Irish in a queue (7)
I believe the answer is:
airline
'transport service' is the definition.
(I know that airline is a type of aircraft operator)
'irish in a queue' is the wordplay.
'irish' becomes 'IR' (abbreviation).
'in' means one lot of letters goes inside another.
'queue' becomes 'line' (a line of people).
'a'+'line'='aline'
'ir' put within 'aline' is 'AIRLINE'.
'puts' acts as a link.
(Other definitions for airline that I've seen before include "company supplying transport" , "It creates inflation" , "Transport business" , "Qantas, for example" , "carrier" .)