Fail to advance entirely, it’s said, without company (8)
I believe the answer is:
lonesome
'fail to advance entirely' is the definition.
I can't judge whether this defines the answer.
'it's said without company' is the wordplay.
I cannot really see how this works, but
'it's' could be 'es' ('e' can mean 'electronic' which is similar to 'IT') and 'es' is found in the answer.
'without' could be 'no' and 'no' is found in the remaining letters.
The remaining letters 'lome' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for lonesome that I've seen before include "Solitary and sad" , "Trail of the - Pine (Laurel and Hardy in Way Out West)" , "Loosen me, being solitary" , "Sad and lonely" , "Are you -- tonight (Elvis)" .)