Turkish bigwig's yearly investing has bombed (5)
I believe the answer is:
pasha
'turkish bigwig's' is the definition.
(I've seen this in another clue)
'yearly investing has bombed' is the wordplay.
'yearly' becomes 'pa' (abbreviation for per annum).
'investing' is an insertion indicator (inserted letters are taken in or invested).
'bombed' is an anagram indicator.
'has' with letters rearranged gives 'ash'.
'pa' placed around 'ash' is 'PASHA'.
(Other definitions for pasha that I've seen before include "High-ranking Turk" , "High ranking Turkish official or officer" , "Turkish high-ranker" , "Turkish title" , "Muslim dignitary" .)