Retiring from transport company surprisingly flush (7)
I believe the answer is:
bashful
'retiring' is the definition.
(thesaurus)
'transport company surprisingly flush' is the wordplay.
'transport company' becomes 'BA' (British Airways).
'surprisingly' indicates anagramming the letters (a surprising ordering of the letters).
'flush' is an anagram of 'shful'.
'ba'+'shful'='BASHFUL'
'from' acts as a link.
(Other definitions for bashful that I've seen before include "one among celebrated seven" , "reserved" , "One of Disney's dwarves" , "Shy and self-conscious" , "Sleepy companion" .)