Article by head worker on excavations at empty house is a hit - it covers everything (3,5,7)
I believe the answer is:
the whole shebang
'everything' is the definition.
(I've seen this in another clue)
'article by head worker on excavations at empty house is a hit it covers' is the wordplay.
I cannot really see how this works, but
'article' could be 'the' (the definite article) and 'the' is located in the answer.
'excavations' could be 'holes' (I've seen this in another clue) and 'holes' is found within the answer.
'empty' could be 'e' (abbreviation e.g. on guages) and 'e' is present in the answer.
'house' could be 'h' and 'h' is found within the answer.
'a' could be 'an' and 'an' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?