Delves into extremes of director's shortcomings (4)
I believe the answer is:
digs
'delves' is the definition.
('dig' can be a synonym of 'delve')
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for digs that I've seen before include "where archaeologists work" , "flat, say" , "Temporary lodgings" , "Lodgings, informally" , "Is very keen on" .)