Floats for purchases to cover first of operations (5)
I believe the answer is:
buoys
'floats' is the definition.
(I've seen this before)
'purchases to cover first of operations' is the wordplay.
'purchases' becomes 'buys' ('buy' can be a synonym of 'purchase').
'to cover' indicates putting letters inside.
'first of' indicates taking the first letters.
The initial letter of 'operations' is 'o'.
'buys' going around 'o' is 'BUOYS'.
'for' acts as a link.
(Other definitions for buoys that I've seen before include "Rises" , "Coloured sea markers" , "Anchored floats" , "Floating markers" .)