Cowboy gear contributing to colossal turnover (5)
I believe the answer is:
lasso
'cowboy gear' is the definition.
(I've seen this in another clue)
'colossal turnover' is the wordplay.
'LASSO' is hidden back-to-front in amongst the letters.
But, I'm unsure how the hidden word is indicated.
'contributing to' is the link.
(Other definitions for lasso that I've seen before include "Somehow catch" , "which may be catching" , "Cowboy's noosed rope" , "One may be caught by this" , "Rope with 20" .)