Hang on to tab -- not hard, it being coppers (3,4)
I believe the answer is:
old bill
'being coppers' is the definition.
(I've seen this before)
'hang on to tab not hard' is the wordplay.
'hang on to' becomes 'hold' (I've seen this in another clue).
'tab' becomes 'bill' (I've seen this in another clue).
'not' indicates named letters should be taken away.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'hold'+'bill'='holdbill'
'holdbill' with 'h' taken out is 'OLD BILL'.
'it' acts as a link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for old bill that I've seen before include "forgotten account" , "pound note?" , "Coppers" , "previous charges" , "The police in the UK" .)