Old man sacked by competent guy? (5)
I believe the answer is:
cable
'guy?' is the definition.
(I've seen this in other clues)
'old man sacked by competent' is the wordplay.
I cannot really understand how this works, but
'man' could be 'ab' and 'ab' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for cable that I've seen before include "Hawser, wire" , "Communications wire" , "Liberal Democrat" , "Telegram; thick rope" , "Thick wire; telegram" .)