Blunder made by foreman? Almost (5)
I believe the answer is:
gaffe
'blunder' is the definition.
(gaffe is a kind of blunder)
'foreman? almost' is the wordplay.
'foreman?' becomes 'gaffer' ('gaffer' can be a synonym of 'foreman').
'almost' means to remove the last letter (most of the word but not all of it).
'gaffer' with its final letter removed is 'GAFFE'.
'made by' acts as a link.
(Other definitions for gaffe that I've seen before include "Clanger" , "A foolish error" , "Tactless comment" , "indiscreet remark" , "A blunder, faux pas" .)