Social changes engulfing team-leader that's resigned (7)
I believe the answer is:
stoical
'resigned' is the definition.
(I've seen this before)
'social changes engulfing team-leader' is the wordplay.
'changes' is an anagram indicator.
'engulfing' is an insertion indicator.
'leader' indicates taking the first letters.
The initial letter of 'team' is 't'.
'social' with letters rearranged gives 'soical'.
'soical' placed around 't' is 'STOICAL'.
'that's' acts as a link.
(Other definitions for stoical that I've seen before include "Impassive" , "Able to bear pain" , "resigned to suffering" , "Showing endurance" , "Indifferent to pain and pleasure" .)