Shunned GI returning stray drone (7)
I believe the answer is:
ignored
'shunned' is the definition.
(I've seen this before)
'gi returning stray drone' is the wordplay.
'returning' shows that the letters should be reversed in order.
'stray' indicates an anagram.
'gi' back-to-front is 'ig'.
'drone' with letters rearranged gives 'nored'.
'ig'+'nored'='IGNORED'
(Other definitions for ignored that I've seen before include "cast aside" , "overlooked" , "Paid no heed" , "Left out in the cold" , "Turned a blind eye to" .)